Had the same problem for random lootboxes.
Blueprint: get lootet Boolean? → No → Spawn random loot → set lootet Boolean true.
How to put this boolean in my save struct without getting every actor variable? I couldnt find an easy way, but I got a small workaround with “Can be damaged”:
Blueprint:
Save:
Load:
Save struct:
I don’t think it’s the smartest solution at all but in my case it helped.