I have solved this problem just before committing this thread, but because I didn’t find any answers or even the same question online, I’ll go ahead and leave the answer here.
Problem:
You import a skeletal mesh (in my case, i am using advanced skeleton in Maya) and the skeleton hierarchy in Unreal includes the geometry within the skeleton hierarchy. This won’t break animations, but the problem that it will cause in the future is that if you change any submesh parts of the character, unreal will think the skeleton changed and will fuss about that. So you want to have a consistent skeleton file…