It would be great if we can get a resolution to this, even down to not needing to deactivate and then reactivate licenses. It’s not sustainable to reactivate licenses when managing a significant number of sites. 🙁
I’m also seeing this issue, albeit with many less admin-ajax.php requests. It feels like loading in all of the blocks at once is not the ideal solution, when it could be done with an intersection observer, or at least some kind of buffer system (or… ideally a toggle to only load the block when you actually click on it’s container)
I’ve replicated this on a second site, simply hitting “update” on the field group assigned to that block type resolves my issue with the ACF block not displaying in the editor.
I had to re-save some of my blocks custom fields in the custom field editor. I don’t really know why some of them needed this while others didn’t, but this solved the issue that appears to be the same one you’re seeing.
I agree, this really should have been something that could be toggled back to the old way.