one site suddenly has 50kb image upload limit

I’m running four sites under one WordPress installation, fully updated, and one of the sites is suddenly stuck on a 50KB per file image upload limit.

Under network settings it’s set to 600KB, which is showing up for the three other sites.

I suspected a recent plugin update as the culprit, but I turned them all off and it didn’t change.

Is there a sub-menu somewhere for limiting individual sites? What else controls this?

One of my editors said when he first encountered the issue, that he began uploading a set of images and then all of a sudden the 50KB limit appeared.

Really weird. Thoughts?