So I had the same problem, where the weaknesses and some buffs didn't go away after becoming human, what worked for me was:
1. Turn your sim into a vampire using mcc(recommend cause worked for me) or cheats to instantly become one
2. Become a grandmaster vampire (which I believe is the highest rank) with a cheatcode
3. Now in the vampire power menu, choose the buffs and weaknesses you still had as a human, so the stomach one and dampened emotions for me.
4. Now that you have them, use a cheatcode WHILE STILL IN VAMPIRE MODE to get rid of the weakness and buff
5. If you now turn into a human using mcc or a cheat to become a human
6. The weakness/buff should be gone!
Cheat: https://sims-online.com/sims-4-vampires-cheats-powers-skills/
1. Turn your sim into a vampire using mcc(recommend cause worked for me) or cheats to instantly become one
2. Become a grandmaster vampire (which I believe is the highest rank) with a cheatcode
3. Now in the vampire power menu, choose the buffs and weaknesses you still had as a human, so the stomach one and dampened emotions for me.
4. Now that you have them, use a cheatcode WHILE STILL IN VAMPIRE MODE to get rid of the weakness and buff
5. If you now turn into a human using mcc or a cheat to become a human
6. The weakness/buff should be gone!
Cheat: https://sims-online.com/sims-4-vampires-cheats-powers-skills/
