screen share problems with guest and slideshow

[Dorothy1]

I regularly join an interest group where the moderator shares a screen that shows a guest's artwork. The system worked just fine on my older iMac today.  But on my new M2 2024 mac mini using a n ew Apple display monitor, I can only see the guest's face, and not the slideshow (which is operated by the moderator).

What could be wrong?  What could be different between the two computers, both running the same zoom presentation on the same day?

PS:  I only turned on the 2nd computer to see if they both had the same problem, but no, they don't.

Thanks.