Screen share option - button does not work

Hello! Sorry to bother you but I am facing serious issue with and I really do not know what to do.
The thing is that we now use jitsi to communicate with kids from our school during the time of pandemic.

Screen share option was working just fine - but then it stopped to work out of the blue. The button for Screen sharing is still there but you can not click on it and it does nothing. For some reason it works just fine on some computers and on the others it does nothing.

I do not understand this stuff at all, so I came to here for help. I tried to look up something in developer stuff at Google Chrome but this is all that i have managed to find. Sorry for the bother and thank you very much! :heart: