That might be the problem. If you include the hip and abdomen bones, the figure might work much better.
Hip and abdomen don't need geometry, but apparently Poser wants the conforming clothing to have the same root bone (hip in this case) as the figure it is being conformed to.
Likewise, the jacket you're making does not have forearm geometry. Still, you should include the forearm bones, since the bend of the forearm can influence the geometry of the shoulder bone.
You can set those bones to invisible, and even hide them from the menu by editing the cr2 - just set hidden to 1 and addToMenu to 0. Make sure you combine those with the statement "off" (which means invisible. Hidden just means the bone will not appear in a hierarchy dropdown).

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