Never seen this one before. . . I have a biped char with a pretty standard IK leg setup. At some point I noticed the feet were sliding around a bit (i.e. when I moved the cog, etc). I thought, "strange" and poked around a bit. The joints are solid, not sliding, but the geo itself is slipping, only on the legs. When I turn on the visibility of the bind joints, the skin snaps back into place and stays there. So if I have the bind joints visibility turned on, we're good. As soon as I hide them, the skin pops off them and starts moving around. I'm in Maya 2017 update 2.
Any ideas what causes this?
Edit: just saw a similar post by nielsvaers from last year. FWIW, viewport 2.0 allows the solution mentioned above (show jnts). Doesn't seem to work in legacy, skin is always slipping. I'm baffled.