I know it’s been a while with this thread sitting here. However, I was having the same problem. Plugging the Body_Opacity into the Opacity Mask as opposed to the Opacity node and then setting the Blend mode to Masked fixed this for me. Works very well for my particular application.
I used Fuse that comes bundled with CC and PS for custom Textures with Mixamo for rigging.
Not sure of another way to accomplish this. Hope this info helps.
