I have two different websites that have been updated to WordPress 5.3 and using ACF Pro 5.8.7, that are now having problems with the parsing of the ACF fields both in the ‘page’ edit page as in the field groups of ACF itself. I’ve added a screenshot of the field group edit page, showing a repeater field. This happens everywhere I’m using ACF in the backend.
The websites are also using the Classic Editor plugin (version 1.5). I tried switching a page to the block editor, but the problem persists.
There weren’t any problems before the update, and I’m a bit stumped. Hope anyone can point me in the direction of a solution.
NB. The front-end of the website is looking fine so far.
It turned out the problem wasn’t ACF, but the used theme. This theme contained code to rewrite <style> tags, which didn’t seem to work that well with WordPress 5.3. Apologies for pointing the finger at ACF.