Post Images Displaying Incorrect Sizes

I use this plugin on my homepage (www.mydarlaclementine.com) to display latest posts. Originally it was working so that three images would line up nicely on one row, and 3 below it (displaying 6 total).

Lately my featured images are being displayed at a different size, messing up the alignment. I had to reduce to showing only 3 latest posts as they scatter oddly across the screen when I do more.

– All featured images are sized at 800×532 in the media library
– I haven’t changed any settings for the plugin

Why are my most recent posts displaying larger images? And how can I fix the sizing so that I can again put 6 posts, to get 3 in one line and 3 in the next?

https://www.ads-software.com/plugins/genesis-featured-content-widget/