i noticed for the parts that dont show that TAB icon isnt next to them so its likley to do with it but im not excactly sure what to do to get the parts i imported to show up on the character im making since theres no tutorials i can find on google
there are tutorials on the character generator on this forum.
basically you have to rename the files before adding them to fit your generator set.
and the tutorials teach you how to rename files correctly.
for now you have to delete all the files you added with wrong names to restore the generator before you can add more files.