This is a bit tricky, and I’ve had a hard time replicating it, but I’m now spending more time trying to work around this issue than working on my game and my tasks are starting to slip behind schedule!
Issue
Referencing derived blueprint classes compiles correctly and runs as expected, yet causes the editor to crash when loading levels or attempting to edit blueprints after saving, exiting and restarting the editor.
Version 4.2.1
Blueprint Project (No C++, Content Only)
What seems to be the issue is referencing and spawning sub-classed pawns (and, sometimes, but not always other sub-classed blueprints)
I have a Pawn class that I’ve sub-classed to create variations. These sub-classes change default values only (However, the bug happens even if the values are not changed). Other classes such as power-ups, HUD, etc. refer to the Pawn by the parent class (Generally by casting) to access variables, events and functions. All of this is pretty typical game design.
When I make reference to these classes in other classes, the game/blueprints compile just fine while running the editor and everything works as expected.
However, once I save the compiled blueprints, exit the editor and reopen the project, referencing these blueprints in any way causes an instant crash.
Here’s video of this happening:
Strange workaround thingy: This isn’t exactly a workaround as it’s unreliable but most of the time, I can load a blueprint that’s isn’t part of the reference tree described above. It takes a few seconds, seemingly recompiling the blueprints, opens the selected BP. then, i can open and edit the problematic blueprints. I mention this as it may shed some light into why this seems to work when I first reference the child classes, but causes a crash when the editor is reopened.