When i select World Composition ,i cannot save my level ro sub level witch is contian instance static mesh actor or HISMC actor

when i select World Composition ,i cannot save my level ro sub level witch is contian instance static mesh actor or HISMC actor. but other levels without instance static mesh actor ro HISMC actor no this kind of issuse,
this issuse only appear world composition. i use instance static mesh actor or HISMC actor for streaming levels without world composition.i can save any level as well.

I test is it in ue 4.18 and 4.16 the same issuse appear