在某些三星设备中，这种情况会发生，因为您需要编写自定义渲染器并尝试设置文本颜色或backgroundcolor，然后它应该可以工作。
或
尝试XLabs Extended Entry

用法：

ExtendedEntry entry = new ExtendedEntry
{
     Text = "Dummy Text",
     TextColor = Color.Black,
     PlaceholderTextColor = Color.Black,
};

PCL编码

using Xamarin.Forms;

namespace VHS.MobileApp.eVita.CustomViews
{
    public class ExtendedEntry : Entry
    {
        /// <summary>
        /// The font property
        /// </summary>
        public static readonly BindableProperty FontProperty =
            BindableProperty.Create("Font", typeof(Font), typeof(ExtendedEntry), new Font());

        /// <summary>
        /// The XAlign property
        /// </summary>
        public static readonly BindableProperty XAlignProperty =
            BindableProperty.Create("XAlign", typeof(TextAlignment), typeof(ExtendedEntry),
            TextAlignment.Start);

        /// <summary>
        /// The HasBorder property
        /// </summary>
        public static readonly BindableProperty HasBorderProperty =
            BindableProperty.Create("HasBorder", typeof(bool), typeof(ExtendedEntry), true);

        /// <summary>
        /// The PlaceholderTextColor property
        /// </summary>
        public static readonly BindableProperty PlaceholderTextColorProperty =
            BindableProperty.Create("PlaceholderTextColor", typeof(Color), typeof(ExtendedEntry), Color.Default);

        /// <summary>
        /// The MaxLength property
        /// </summary>
        public static readonly BindableProperty MaxLengthProperty =
            BindableProperty.Create("MaxLength", typeof(int), typeof(ExtendedEntry), int.MaxValue);

        /// <summary>
        /// Gets or sets the MaxLength
        /// </summary>
        public int MaxLength
        {
            get { return (int)this.GetValue(MaxLengthProperty); }
            set { this.SetValue(MaxLengthProperty, value); }
        }

        /// <summary>
        /// Gets or sets the Font
        /// </summary>
        public Font Font
        {
            get { return (Font)GetValue(FontProperty); }
            set { SetValue(FontProperty, value); }
        }

        /// <summary>
        /// Gets or sets the X alignment of the text
        /// </summary>
        public TextAlignment XAlign
        {
            get { return (TextAlignment)GetValue(XAlignProperty); }
            set { SetValue(XAlignProperty, value); }
        }

        /// <summary>
        /// Gets or sets if the border should be shown or not
        /// </summary>
        public bool HasBorder
        {
            get { return (bool)GetValue(HasBorderProperty); }
            set { SetValue(HasBorderProperty, value); }
        }

        /// <summary>
        /// Sets color for placeholder text
        /// </summary>
        public Color PlaceholderTextColor
        {
            get { return (Color)GetValue(PlaceholderTextColorProperty); }
            set { SetValue(PlaceholderTextColorProperty, value); }
        }

        public static readonly BindableProperty BorderRadiusProperty =
        BindableProperty.Create<ExtendedEntry, float>(p => p.BorderRadius, default(float));

        public float BorderRadius
        {
            get { return (float)GetValue(BorderRadiusProperty); }
            set { SetValue(BorderRadiusProperty, value); }
        }

    }
}

机器人代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Xamarin.Forms.Platform.Android;
using Xamarin.Forms;
using VHS.MobileApp.eVita.CustomViews;
using Android.Graphics;
using Android.Text.Method;
using Android.Util;
using Color = Xamarin.Forms.Color;
using VHS.MobileApp.eVita.Droid.CustomRenderer;
using System.ComponentModel;
using Android.Text;

[assembly: ExportRenderer(typeof(ExtendedEntry), typeof(ExtendedEntryRenderer))]
namespace VHS.MobileApp.eVita.Droid.CustomRenderer
{

    public class ExtendedEntryRenderer : EntryRenderer
    {

        protected ExtendedEntryRenderer(IntPtr javaReference, JniHandleOwnership transfer)
        {

        }

        public ExtendedEntryRenderer()
            : base()
        {

        }

        private const int MinDistance = 10;

        /// <summary>
        /// Called when [element changed].
        /// </summary>
        /// <param name="e">The e.</param>
        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            var view = (ExtendedEntry)Element;

            if (Control != null && e.NewElement != null && e.NewElement.IsPassword)
            {
                Control.SetTypeface(Typeface.Default, TypefaceStyle.Normal);
                Control.TransformationMethod = new PasswordTransformationMethod();
                this.Control.SetBackgroundColor(Android.Graphics.Color.White);
            }

            #region SETTING CUSTOM FONT

            if (view.FontFamily != null && view.FontFamily != string.Empty)
            {
                Typeface typeface = Typeface.CreateFromAsset(Forms.Context.Assets, view.FontFamily);
                Control.Typeface = typeface;
            }

            #endregion

            // SetFont(view);
            SetTextAlignmentWithVerticalFill(view);
            SetPlaceholderTextColor(view);
            SetMaxLength(view);
        }

        /// <summary>
        /// Handles the touch.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="Android.Views.View.TouchEventArgs"/> instance containing the event data.</param>
        /*void HandleTouch(object sender, TouchEventArgs e)
        {
            var element = (ExtendedEntry)this.Element;
            switch (e.Event.Action)
            {
                case MotionEventActions.Down:
                    this.downX = e.Event.GetX();
                    this.downY = e.Event.GetY();
                    return;
                case MotionEventActions.Up:
                case MotionEventActions.Cancel:
                case MotionEventActions.Move:
                    this.upX = e.Event.GetX();
                    this.upY = e.Event.GetY();

                    float deltaX = this.downX - this.upX;
                    float deltaY = this.downY - this.upY;

                    // swipe horizontal?
                    if (Math.Abs(deltaX) > Math.Abs(deltaY))
                    {
                        if (Math.Abs(deltaX) > MinDistance)
                        {
                            if (deltaX < 0)
                            {
                                element.OnRightSwipe(this, EventArgs.Empty);
                                return;
                            }

                            if (deltaX > 0)
                            {
                                element.OnLeftSwipe(this, EventArgs.Empty);
                                return;
                            }
                        }
                        else
                        {
                            Log.Info("ExtendedEntry", "Horizontal Swipe was only " + Math.Abs(deltaX) + " long, need at least " + MinDistance);
                            return; // We don't consume the event
                        }
                    }
                    // swipe vertical?
                    //                    else 
                    //                    {
                    //                        if(Math.abs(deltaY) > MIN_DISTANCE){
                    //                            // top or down
                    //                            if(deltaY < 0) { this.onDownSwipe(); return true; }
                    //                            if(deltaY > 0) { this.onUpSwipe(); return true; }
                    //                        }
                    //                        else {
                    //                            Log.i(logTag, "Vertical Swipe was only " + Math.abs(deltaX) + " long, need at least " + MIN_DISTANCE);
                    //                            return false; // We don't consume the event
                    //                        }
                    //                    }

                    return;
            }
        }*/

        /// <summary>
        /// Handles the <see cref="E:ElementPropertyChanged" /> event.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="System.ComponentModel.PropertyChangedEventArgs"/> instance containing the event data.</param>
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            var view = (ExtendedEntry)Element;
            this.Control.SetBackgroundColor(Android.Graphics.Color.White);
            //if (e.PropertyName == ExtendedEntry.FontProperty.PropertyName)
            //{
            //    SetFont(view);
            //}
            //else

            if (e.PropertyName == ExtendedEntry.XAlignProperty.PropertyName)
            {
                SetTextAlignmentWithVerticalFill(view);
            }
            else if (e.PropertyName == ExtendedEntry.HasBorderProperty.PropertyName)
            {
                //return;   
            }
            else if (e.PropertyName == ExtendedEntry.PlaceholderTextColorProperty.PropertyName)
            {
                SetPlaceholderTextColor(view);
            }
            else
            {
                base.OnElementPropertyChanged(sender, e);
                if (e.PropertyName == VisualElement.BackgroundColorProperty.PropertyName)
                {
                    this.Control.SetBackgroundColor(view.BackgroundColor.ToAndroid());
                }
            }
        }

        /// <summary>
        /// Sets the text alignment.
        /// </summary>
        /// <param name="view">The view.</param>
        private void SetTextAlignmentWithVerticalFill(ExtendedEntry entry)
        {
            switch (entry.XAlign)
            {
                case Xamarin.Forms.TextAlignment.Center:
                    Control.Gravity = GravityFlags.Center;
                    break;
                case Xamarin.Forms.TextAlignment.End:
                    Control.Gravity = GravityFlags.End | GravityFlags.CenterVertical;
                    break;
                case Xamarin.Forms.TextAlignment.Start:
                    Control.Gravity = GravityFlags.Start | GravityFlags.CenterVertical;
                    break;
            }
        }

        /// <summary>
        /// Sets the color of the placeholder text.
        /// </summary>
        /// <param name="view">The view.</param>
        private void SetPlaceholderTextColor(ExtendedEntry view)
        {
            if (view.PlaceholderTextColor != Color.Default)
            {
                Control.SetHintTextColor(view.PlaceholderTextColor.ToAndroid());
            }
        }

        /// <summary>
        /// Sets the MaxLength characteres.
        /// </summary>
        /// <param name="view">The view.</param>
        private void SetMaxLength(ExtendedEntry view)
        {
            Control.SetFilters(new IInputFilter[] { new InputFilterLengthFilter(view.MaxLength) });
        }
    }
}