Hi there I am using WordPress 5.0 and ACF Pro 5.7.8 and have also discovered this bug.
I had a repeater with required fields and have had to switch the required attribute off in order to be able to save the post.
I have a similar issue and any help would be greatly appreciated.
I also do not have any caching plugin running and am using ACF Pro 5.5.10.
The bidirectional update seems to be working and when I add a CPT to the first field and save I can go into the edit screen for the that CPT and see that the second field is updated.
The problem is that when I go to the template (that uses the second field) there is no data coming through for that particular field. If I return to the admin and update the CPT (and the second field) on returning to the frontend I can now see that there is data coming through for the second field?
Not sure why this would be happening as the update_field code appears to be working correctly as I would not see any CPT’s in the second field if it wasn’t.
Is there some step in the update process that isn’t running?
Why don’t you use json_encode() to create a JSON version of the array that you pass into register_field_group(), then all you need to do is create group key for the fields (I think it may have been the id field in previous versions), then create a json file following the acf conventions and drop it into your theme’s acf-json folder…
I have just done this and was able to sync the fields back into the database.
