hey ,
your linked question solved my problem!
I had some item class in my struct which i did’t set / were set to none. after i set them to the their bp class, the warning went away!
so thanks for giving me something to think about and try out!
sadly that wont help u much with your problem, i think, as you said you need your classes to be empty while saving. hope somebody can help you out with it. all the best and good luck.
and thanks again to jimd667 for trying to help me out as well!