Strange Mesh Bending - G3M

The most recent background info I can provide here is that I've installed a number of new products, both G3F and G3M and have noticed an accompanying issue with the way the g3m mesh bends at the shoulders now.
At base pose things look fine, but as you can see in the pictures bending the arms down causes odd crumpling of the mesh underneath and around the arms. Any ideas? I have no clue where to start with this...


BeforeBend.jpg
1400 x 1000 - 175K


AfterBend.jpg
1400 x 1000 - 171K
Comments
Is one of the products you installed by any chance Skinchangers by Sixus1? That has a problem that's come up a few times. Although I thought that had been fixed by now.
It is! I manually installed too, I'm fine with ditching it. Thanks so much for the input!!!!