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The issue most likely has to do with the skin & bone animation. The polygon collider will not update itself every frame while the sprite is animating.
Your best option would be to use a simple collider instead, but if you really need it to be very accurate, you'll need the colliders to be placed on the objects and updated as they rotate/move around.
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You can use Leshy's tools to split non uniform spritesheets: https://www.leshylabs.com/apps/sstool/
Your spritesheet is 32x32. I've used it before:
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