i tested it on a fresh viwi with no changes to the blendshapes and still got clipping and issue with pose changes- i have more images but cant upload more than 1 at a time
Matched those blendshapes in blender and I don't have that issue on the thigh.
Now I suspect that there's armature mismatch? Did you first Append the harness in Blender to the Viwi, assign them both to use the same Armature and then export that to Unity?
ahhh ok i see no its not goanna change anything with path mode... i manually parented the armature to see if the link was causing any issues and its not so it seems its a unity/vr chat issue... im going to have to either manually fix some weights or do some corrective blendshapes
im really not happy with this.... iv tried fixing this in many ways and its not working at all so now i have a asset iv paid for that does not work for vrchat
Last thing I can think of is to check/apply transfomations in Blender. But as you say the problem only occurs once in Unity. Could it be that there's confusion with bones/vertex groups in Unity, where the harness wants to 'follow' another bone of similar name?
i tested it on a fresh viwi with no changes to the blendshapes and still got clipping and issue with pose changes- i have more images but cant upload more than 1 at a time 
only the male chest, everything else is at 0