No video in MediaPlayerElement

[JMvanderDuim]

I'm using a media player element in a winui3 application. But when I attach an uri and say play. I do get the audio but no video is playing. The same goes for the Azure Communications Calling win ui3 example/tutorial:

https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/voice-video-calling/get-started-with-video-calling?pivots=platform-windows

There is winui3 sample code. This is also to be found on GitHub. Als no video is showing.