Object in another map?

I have two maps in my project built by UE4.12.5

A map named ‘LoadFS’, the other map named ‘FS’ which ia a sublevel of ‘LoadFS’

A character blueprint named ‘CH_FuShi’ is in ‘LoadFS’

I have modified the details of the character blueprint named ‘FirstCharacter_K’ in ‘FS’

Then there is a message dialog when i want to save the map ‘FS’, what ever the current map is ‘LoadFS’ or ‘FS’: