ImageSource.FromStream fails on Windows Phone with Invalid cross-thread access exception

I have an image that is data-bound to ImageSource object. It works on Android but fails on Windows Phone platform. I've tried multiple ways to initialize ImageSource:

• ImageSource.FromStream(()=>GetMyMemoryStream());
• ImageSource.FromResource(resourceUri.ToString());

but all of them fail with cross-thread access. It appears that internally Xamarin.Forms.ImageSource is using a Task and when the task runs it uses non-UI thread.

Any workarounds?

Thanks!