Link to a page where the issue can be seen: hidden link
However, I just came back to the page and notice the images at the bottom of the page are displaying in full size, rather than being cropped to 225px x 225px like the toolset code says.
The update of Themify Ultra must have added some image lazy loading which threw off the custom image sizes, as you suspected. I was able to disable that feature and the correct image sizes returned. It's a shame because the lazy loading helps the page load faster, but at least the formatting is back now. Thanks for your help!