You're using a hair mod- are you also using Skara's hair texture mod? If so, that's your culprit. If you're using any facial texture mods, you'll need to remove those, too. Also, some hair mods (I know there are some recent ones by Adela) include built in textures, if you're using one of those, you'll need to take them out, too. Hair mesh mods are fine (though some don't show up in Trespasser), but textures will cause you problems. This has been a problem with all DLCs, unfortunately. Mods which change gameplay elements should be fine, too (though again, some won't work in Trespasser or other DLC), and I believe there are now even a few Trespasser specific formalwear mods (if you try to use old ones not made for Trespasser, you'll likely have issues).
Hope that helps. 🙂
