Unfortunately, it appears that Consistent Power Armor Overhaul is not the cause. Disabled it, alongside Power Armor Materials and Paints and More Power Armor Mods and the fists/hands still appeared. One difference I notice between the vanilla profile and the modded one is that the T-45 Armor at the start has a star on its chest. Not sure what mod is responsible for that, or if its relevant. EDIT: Managed to figure out which mod was causing it. For reasons unknown to me LooksMenu Body Tattoos seemed to be making the fists/hands appear.