In the past, I had this problem quite frequently with circular dependencies in blueprints. I know UE4 handles them a bit better now, but I assume a complex blueprint with a lot of references could still have the same problem. This occurs when you are dynamic casting to other blueprints:
- Blueprint A dynamic casts to Blueprint B to access a variable in blueprint B
- Blueprint B casts to Blueprint A to access a variable in blueprint A
- When you begin to load Blueprint A, it tries to load Blueprint B, which Blueprint A depends on
- Blueprint B depends on A, and it tries to load Blueprint A
The biggest solution to this is using blueprint interfaces or casting to a C++ parent class.
As I stated previously, Epic has done a lot of work to fix circular dependency problems, but I assume they would still occur with a lot of dependencies. If you haven’t been using interfaces, I would assume that would most likely be the reason for crashing. The reason it would work in another editor is because the blueprint (most likely) would throw an error when it can’t load certain dependencies.