OK, I may have found the problem.
Did you convert to CC3+ character? I just loaded a CC3 character in CC4 and the Appearance Editor could not be opened. So I'm converting it to CC3+, which may take a while (it's not done while I write this).
The issue is that the old Appearance Editor used Substance for everything, whereas the new one uses a different approach for skin and makeup (SkinGen).
You might try converting to CC3+ in CC3 first, because I don't remember it taking so long. (But you mentioned that you don't have the CC3 version anymore...)