Problematic screen sharing

Hello Everyone!

I have had this problem for a few weeks already and so far couldn't fix it:

On a meeting, when I share my screen, the image windows of other people get compressed and squeezed, so much that I no longer identify the atendees. It's really weird and troublesome, because I don't what people are doing, I just can't see anyone properly.  It is even weirder because the images are shown right in the recording later on.

I have already searched for updates and apparently it's ok. I have also looked extensively for solutions, to no avail. 

Has anyone had this problem or could anyone help me with this, please? 

Many thanks in advance!

Canoeira