Do not panic, this is of no importance at all, In the preview window on the right, you can see that the face looks normal but the body doesn't look normal at all. In the example below, I'm using 'EncBandit04MissileNordF' as a base object for Griselda. Consequently, you'll have to be careful about your choice, especially if your npc must use some vanilla dialogue because you won't be able to modify its voice type. Modifying them would create the dark face bug you are trying to avoid.
Once you have picked up a base actor for your npc, all the data on the 'Traits' tab of your npc form will be greyed out so that you cannot modify them. Do not edit the base actor you have chosen. in the actor form, in 'Template Data', in 'ActorBase' choose the model your npc will use and select 'Use Traits' (leave the other data alone unless you know what you are doing). create an entirely new npc from scratch, DO NOT DUPLICATE AN EXISTING NPC, This short tutorial is meant to help about that. The dark face bug is everywhere and it's a big problem when you are creating new npcs in a mod specifically made for the PS4.
