Summary blocks are turning identical

Site URL: https://www.severnvineyard.org/sunday-talks-new-layout

I'm trying to build a page with multiple summary blocks to highlight and group blog content from different categories.

The editor behaves as expected while editing and saving. I can set up a block for each category as desired, save it and see this works correctly outside the editor.

But when going back in to edit the page, I find that summary blocks switch from having different settings to identical settings. This makes all the blocks identical, and needing to be reset manually before saving and exiting again.

It's very annoying, and the first time I've seen this happen, but I am seeing this consistently on multiple pages today. What's wrong?