Warning : None of them were set as the actor's RootComponent

I ’ m getting this warnings when try to compile Parent" Master Part".

LogActor: Warning: Part_Engine_C /Engine/Transient.World_29:PersistentLevel.TestEndine_GEN_VARIABLE_TestEndine_C_CAT_1 has natively added scene component(s), but none of them were set as the actor's RootComponent - picking one arbitrarily

Getting this warnings from all Master_Part’s children.

And the BP looks like that :

And i dont know if its important but compiling this BP takes about 1-2 mins with I9 CPU and 32 GB ram.

Any idea how to fix that,
Thanks .