Black screen on android using community server meet.jit.si

Hi There,
i use the community server meet.jit.si
on my Samsung S8 with android 9 in the jitsi-app all is black:
only the own screen shows the own video.
with the S8 i can’t see the others, and the others can’t see me.
on the S8, the servers Certificate is valid.

On a (older) Samsung TAB A6 with android 5.1.1 all works well.

Any idea, what i can do ?

regards
Koni