This is driving me bonkers. I have checked and the two meshes are identical (the teen is an age conversion of the adult). The alphas are identical too, yet as you can see from the pictures only the teen has the bottom only dress bleeding onto the arms. From what I thought I knew, both should have the bottom only dress showing because the arms are set to 'top', but the adult doesn't. The bottom only dress is also identical in the alphas.
Does anyone know of anything else that might be causing the difference?
It's never uncomplicated lol. Turns out that I had two adult meshes for the same top and the one that was being used wasn't the one I was looking at. The second one had the arms included in the corset group instead of the top group. So I have deleted the unneeded mesh and changed the teen one to match and it all works now. XD