Thanks for the info.
I’ve got over 60 field groups, some of them are flexible fields with several of the other field groups as clones inside their flexible field layouts.
Notices started to pop up after I’ve duplicated the field groups via WPML (WordPress Multilingual Plugin) functionality to make the field groups available in other languages.
I did not consider the hierarchy of the fields while duplicating them. Meaning: I should have duplicated the ones which are used as clones first. And only after duplicating all the basic field groups I should have started with duplicating the rather complex ones.
–> Might be the reason why I get these notices now.
