I had the same issue when I loaded an old save where third party mods were enabled. The only thing that worked for me was clicking on randomize appearance first, and then going back and re-selecting the things I want. It is tedious but it worked.
And be careful because the "randomize appearance" may give your Tav different types of genitals when you had the opposite selected for them before, and that can easily go unnoticed. So you'll have to go back and re-select that too.
