I have a custom post type (“Directory”) with a custom taxonomy (“Teaching Area”). Running ACF 5.12.3, updates to the taxonomy won’t go through – the page says it updates, but “update” box freezes, and the changes aren’t saved.
HOWEVER, running identical plugins/themes/database on my dev environment (just overwrote the dev database today with the prod database), updates still work. I can’t fathom what’s going on.
I might have narrowed it down a little, or this might be a red herring. Using the network analyzer, I can see the dev server sends a POST request to admin-ajax.php with the appropriate fields that looks like this: