Nextcloud Talk Screenshare Problem


i use NC 15 with talk version 5.0.3. i have also set up a turn server so i can video chat with friends on the other end of the world. Audio and video works very well. As soon as I make Screenshare the videochat connection breaks down or no connection to the videochat is established.
When I make a screenshare, my friends only see a black screen and no audio or video connection. Rotating circles only
What could be the reason?
I would be grateful for any help.