I would also be curious how you got that to work because I ran into the same issue as DaUik when trying to use that guid, it was unavailable in packaged builds.
I was able to get around it by copying it into a custom component purposely built to persist that value. But the callbacks that make that work are specific to C++ and therefore not a viable solution for a blueprint discussion.
But it was worth it to not have to deal with the hooks for actor creation, duplication and whatnot that the Engine already deals with to manage the guid that DaUik referenced.