No real solution found BUT I have identified the source of the problem : Elementor.
If you go to Elementor and edit the model corresponding to the post that you are editing in Gutenberg, you’ll probably see that the preview settings of Elementor have been reset to a post that has nothing to do with the model that you are editing. This happens all the time since a while. So, if you update the previewing settings so that the Elementor editor uses your target post for previewing, the previewing in Gutenberg will now work correctly.
Not satisfactory since our editors and authors cannot adjust the Elementor preview settings so that Elementor uses the post that is currently edited in Gutenberg but at least we kbow where the problem is. Not an ACF problem.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!
© 2022 Advanced Custom Fields.