For whatever it may be worth, I captured a stack frame, surrounding asm, and register values during one of the import-crashes I see. I’ve looked at a few, and the stack frames are always very similar.
I’m not running a pure debug build of the engine, so couldn’t see symbol values, and neither am I familiar with the UE code, but it looks to be happening in GUI code, which is consistent with the crashes I see: they are always when I take some GUI action, like closing the SM editor window, or dragging something into the main view after asset importing.
Here it looks like register RDI contains a non-pointer value, and is being indirected. It is read from an offset into a structure pointed to by RBX, and RBX does appear to contain a good pointer. Eyeballing the C++ code that matches this asm, I’m guessing rbx is the ‘this’ pointer, and rdi with the bad pointer is the DelegateInstance.
What a DelegateInstance is or why it’s a bad pointer during deletion, I have no idea.
Attached: Stack.zip.