Apocalypse production issues were the result of Singer going AWOL on set. He did it with Bohemian Rhapsody. Apparently, he also did the same with DOFP Superman Returns.
I honestly don’t think that was much of a problem.Did the Studio make decisions that slightly tied his hands? Yes. But also people have said they learned the wrong lessons from Apocalypse especially that the story needed to be smaller and that also helped with the issues with telling the Phoenix story in this film. I mean Kinberg was a big cheerleader of the more "Grounded" approach to this film while making it.