所以，我无法解决保存到首选项的问题，也无法得到一个明确的错误消息，因为它是一个发布版本，不能连接到VS进行调试，在那里我可以看到我的控制台打印语句在我的try/catch块。我想一个解决方法是尝试在警报中打印这些消息，如下所示：DisplayAlert("Alert", "<error message body here>", "OK");
然而，我确实找到了一个有利可图的解决方案，那就是将我的JSON对象和字符串保存到如下文件中：

public class LocalStorageService {
    private string documentsFolder;

    public LocalStorageService() {
        this.documentsFolder = FileSystem.AppDataDirectory;
    }

    public string ReadTextFile(string fileName) {
        string data = null;

        try
        {
            string path = Path.Combine(documentsFolder, $"{fileName}.json");

            if (File.Exists(path))
            {
                data = File.ReadAllText(path);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error in LocalStorageService::ReadTextFile(): {ex.Message}");
    }

        return data;
    }

    public void WriteToFile(string fileName, string json) {
        try
        {
            string path = Path.Combine(documentsFolder, $"{fileName}.json");
            File.WriteAllText(path, json);
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error in LocalStorageService::WriteToFile(): {ex.Message}");
        }
    }
}

我调用保存和阅读如下：

//write
localStorageService.WriteToFile(LocalStorageItemNames.USER_PROFILE, JsonConvert.SerializeObject(profileModel)

//read
string model = localStorageService.ReadTextFile(LocalStorageItemNames.USER_METAS);
if (!string.IsNullOrEmpty(model)) {
    profileModel = JsonConvert.DeserializeObject<ProfileModel>(model);
}