StaticMesh (CombinedMesh) looks weird on android device.

Hi, first of all i am very sorry for my poor english.

MyScene has several static mesh ( combined mesh ).
When render on editor or ios, it looks normal and nice but when render on aos device it looks weird.
It seems like broke vertex.
I have no idea what happen here.
If you know reason or have any hint, please let me know.

Thank you.

Upper image is normal rendering.
Down image is weird rendering. Bird wood statue’s right eye is distorted.

When i uncheck position in vertex compression setting, the wooden statue render normally!!!
I try to find out WHY

If anyone know about this weird situation, please let me know