The code
Stream _stream = new MemoryStream();
await this.richTextBoxAdv.SaveAsync(_stream, Syncfusion.UI.Xaml.RichTextBoxAdv.FormatType.Html);
Causes the following error:
The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD
Thanks for your help
Daniel