On 5.4.4. I had the same
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff
but with a different stack trace to you.
In my case, as far as I can tell, it was caused by 2 C++ methods exposed to blueprint that had the same name (but different signature). 1 was in fact an interface method. Re-naming 1 of them, clearing the Binaries & Intermediate folders, and rebuilding seems to fix this.
I assume this is a given of the Unreal architecture that blueprint will lose reference to which of the “same-named” functions are being called and thus throw this horrid exception.