I thought we touched on this, but in any case, Blend Shapes are currently not officially supported out of the box.
The architecture is set up to allow this though it’s not actually hooked up in the Maya or Mobu plugins. We need to make some code changes on our side to support this. I don’t have an ETA as to when those changes will go in, but will update this thread after I’ve gotten some more information from our devs.