Hi,
I am getting the exact same issue. Strangely, it did work properly for 3 months now, so I did create 22 fields groups as I do have various custom post type. It is becoming quite blocking, as I cannot get access to the field groups for modifications easily, and I am at the ending stage of the current project…
Almost all the plugins installed are custom.
ACF Pro: V 5.4.8
Wordpress V 4.5.3