Sharing in Firefox fails

First, I wanted to say that I am impressed with jitsi meet and I like it very much. Unfortunately, just at the start I run into a big problem: during a meeting person A shared a window in Firefox/laptop, from their perspective everything looked ok. From my perspective (chrome/laptop) I saw a frozen last frame before the presentation started, it was only this frame until person A stopped sharing. This happened with sharing windows, as well as sharing screen. What happened? Is there a way to fix it?