Hi there esmi, thanks for the input.
I had already tried deactivating the plugins, but that didn’t work.
Switching themes allowed the site to load, so I thought it was likely a problem with Atahualpa.
Reloaded a fresh download of that, but still had the same problem.
Had to do fresh re-installs of both WP and Atahualpa from new downloads for it to work.
I have no idea what happened, but it certainly was time consuming to fix.
Now trying to figure out why it does not display spaces after commas in posts and pages.