I'm working with the new Muscle and Tissue Simulation and noticing the solver does not output the tissue_outer_surface group that is being referenced in the deform_skin subnetwork. Has anyone found any work arounds just yet?

That's because you are in Fascia mode instead of full Tissue mode.

The "deform_skin" subnet is designed to be used with the full Tissue mode, so to do this, set the "switch_sim_tissue" input to "1".

If you want to deform the skin with the fascia only (not really recommended for Otto, but might make sense for very lean characters that don't have any body fat) then you can change the group in the blast node to "tissue_core_surface".