出现此问题的原因是<table>位于<center>内部。
请尝试删除<center>元素。

编辑：

此问题现已在当前最新的错误修复版本中得到解决：https://www.gemboxsoftware.com/spreadsheet/nightlybuilds/GBS47v1336.zip
在当前最新的NuGet软件包中：
Install-Package GemBox.Spreadsheet -Version 47.0.1336-hotfix

我同意乔纳森·伍德的观点。
最好分两步进行：

1. Parse the HTML table with the HTML Agility Pack NuGet package.

var query = from table in
            doc.DocumentNode.SelectNodes("//table").Cast<HtmlNode>()
            from row in table.SelectNodes("tr").Cast<HtmlNode>()
            from cell in row.SelectNodes("th|td").Cast<HtmlNode>()
            select new {Table = table.Id, CellText = cell.InnerText};

1. Use EPPlus and its LoadFromArrays method.

string firstName = "Bob";
string lastName = "Burton";
DateTime dateOfBirth = new DateTime(2000, 1, 1);
var testData = new List<object[]>()
                {
                    new object[] {"First name", firstName},
                    new object[] {"Last name", lastName},
                    new object[] {"Date of birth", dateOfBirth}
                };

using (var excelPackage = new ExcelPackage())
{
    ExcelWorksheet excelWorksheet = excelPackage.Workbook.Worksheets.Add("Test worksheet");
    //Load the summary data into the sheet, starting from cell A1. Print the column names on row 1
    excelWorksheet.Cells["A1"].LoadFromArrays(testData);
}