I have posted on unreal answer hub as well - because this is super confusing to me
Hmm, so is that “switching” between levels?
Well, i’m no expert at that (especially that I never used the streaming), but I once had a issue with my mission points that the second Entry Mission wouldn’t be destroyed in the game reload even when I complete the whole mission, it turned out that my LoadGame using the Event Tick (this part was on my PlayerController) was bugging it, all I had to do was switch to the Event Begin Play as I didn’t even need the Event Tick for it anymore.
So I believe that it could be an issue with the Event Tick at your project causing some sort of conflict, did you try to do without streaming, but using the normal OpenLevel?
Also, it might be too a case that the new loaded map in the streaming is actually reseting you BP stuff just like the OpenLevel would do, in that case you would use a custom GameInstance or use the SaveGame system.