This is related to this post : Hot Reload errors since upgrade to 4.8.1 - Blueprint - Unreal Engine Forums
Just wanted to make it more visible in BUG REPORTS so it gets fixed.
Delegate declaration inside the class declaration gets broken after a hot reload. For some reason, the UField linked list is broken when searching for BlueprintCallable UFunctions.
I believe this is a bug in the HotReload, since the initial compilation works correctly. However, all the functions are correctly remapped, so it’s somewhere else that the “Next” link gets nulled, don’t know where, but when I noticed this only happened on _DelegateSignature, I promptly removed them from my problematic classes solving my issue.
//Do not put this inside the class declaration, put it outside DECLARE_DYNAMIC_MULTICAST_DELEGATE(FOnMakeMeExplodeAfterHotReload);
To be fair, in the source most of those are done outside class declaration but some are not. If this is not intended to be in the class declaration UBT should warn me so!
This was pretty frustrating to debug to say the least. Also, it was working in versions of the engine prior to 4.8…