Child component has no collision

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Box is a box collision component, with simulate physics enabled and gravity and collision disabled, as shown:
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SkeletalMesh is a plane model with physics asset, with simulate physics disabled and collision presets set to BlockAllDynamic.

With above settings, when I drag this blueprint into the map, SkeletalMesh do have collision and my character can even stand on it:

But, however, when I drive the plane, it collides with nothing at all (the plane movement logic applies all forces to Box):

When I enable simulate physics for SkeletalMesh, SkeletalMesh just leaves Box like they’re 2 independent actors instead of parent and child, but SkeletalMesh retains its collision and collides with ground again.

Why does SkeletalMesh have no collision when my character drive the plane?
Why does it leave Box when simulate physics is enabled?
I just want Box and SkeletalMesh fixed together and SkeletalMesh always with collision, so SkeletalMesh always moves with Box no matter simulate physics is enabled or not.