I’m experiencing the same problem. I add a new ACF field group with three field types (Post Object, Page Link & Relationship) to a CPT, e.g. “Resources”. For each of the three fields I select the “Event” CPT (tribe_events) for the “Filter by Post Type” option.
When I open a “Resource” for editing, each of the three ACF field populate with the list of events. I then select the event(s) I want and hit the Save/Update button. Upon post back, all three ACF fields are empty.
I find that switching to any other post type works fine, and the selections are saved.
