Well, I resolved the issue by replacing Tristan with a whole new sim. I guess the sim itself was corrupted, because only Tristan causes problems. Thank you for offering help though @jpkarlsen !
I just tried it, he was not there. And in fact, once I returned from CAS back to live mode, the sim disappeared completely, I can't even see him in my other sims relationships anymore, even though he should be there
Unfortunately your savegame became corrupted. Start a new game and make sure all your Mods and CC are updated.
As I expected since I tried that once already, it did not help. I made everything again, placed the household in the world and the problem still persists. For some reason the game acts as if my sim just doesn't exist.
Well, I resolved the issue by replacing Tristan with a whole new sim. I guess the sim itself was corrupted, because only Tristan causes problems. Thank you for offering help though @jpkarlsen !
