Misaligned Thumbnail Previews after the Update

Hi, I have posted this question before, but somehow my thread disappeared without being resolved.

After the genesis update I believe in March, my thumbnail previews are out of alignment.

I had two featured posts with full size pictures and then underneath two columns of thumbnails (300×300 pix) under them. After the update, I still have the two featured posts with full size pictures, but the thumbnails are only in one row, with every other one moved a tad closer to the middle than the previous one.
This is not something with the theme, because no code changes were made with the theme when this happened.
Please advise as to what can be causing this.

Thanks!

Marina

https://www.ads-software.com/plugins/genesis-grid-loop/