Game Top frame object disappearing

Hi everyone,

I’m currently developping a new “test” game with animation and dialogs.
But … I’m facing an issue …
I have a character made of 2 large object (2 body parts) each of those mesh have about 40 vertexGroups in them and are are controled by a general armature.
My problem is that when the game is launched each object are shown until the camera slowly go down:

Have you guys ever dealed with this issue, does anyone have an idea on how to fix this ? (maybe the armature “new position”)
Thancks in advance…