So, here's the problem: I was playing my legacy family as usual when all of a sudden, I got a notice about their townie friend having a stuck aging check (via Nraas' Overwatch). Instead of eventually aging up on their own, though, she remained stuck for several days, so I tried to age her up manually.

I opened the lot with MasterController, and clicked on the Sim > Trigger Age Transition. The sim faded out of view, but instead of reappearing as a teen, she just... disappeared. Completely. I checked the lot from View Town; she wasn't in the house. I switched households. She was gone from the panel. I figured Overwatch would get her back, but another few days passed, and nothing changed. I tried Resetsim. Still nothing.

I reloaded my pre-MC-messing-around save and tried to bring her back by switching households via Edit Town instead. I had her mother invite her over (??) and added her to the household via MC. Aging up still didn't work, so I reset her via MC. She became a pudding-face all of a sudden (???), but at least it worked after that.

Satisfied with this, I reloaded my save again and tried to do the same from my legacy family, but in a different order. Invited her over, used reset sim via MC (she reappeared in the household as she should, showing up on the lot from town view). Tried Trigger Age Transition again. This time, she disappeared again... and now I can't even invite her over anymore. Whenever I do, I just get an ErrorTrap message. These are the things I've tried since:

- Resetsim cheat via ctrl+shift+v - did absolutely nothing
- Switch to her household and try to invite her over - still gets ErrorTrap
- Add her to the household via MC (both her active one in one attempt, and my legacy household in another) - nothing happens, although she shows up in the list when you try to split the household from Edit Town
- Split her up from her active household (tip from some older thread dealing with similar issue) - she won't go to the clipboard, nor will she show up in the household (regardless of it's her actual one or my legacy one in both attempts). If you try to move her out with another sim, both will disappear. If you return to the game for the active household, you'll return to a messed up UI with no sim panels, moodlets showing but no sim selected, no way to click on anything besides play/pause/etc, inability to go to buy/build mode.

Her icon is now blanked out, even though she's still listed as a child in MC (the first time she was gone, she at least still had her icon left), and if I switch to her household she doesn't show up in their relationship panel for household members. Overwatch won't retrieve her, either. The stupidest thing is that I accidentally overwrote my pre-MC save, so I can't reload that, either.

I could've just ignored the issue, but since then there've been a bunch of other problems with my town:
- a LOT of lag
- sims changing into wrong special/career outfits (for example, bunny hat instead of graduation cap, everyday outfit instead of work one)
- user-directed actions being applied to the wrong active sim
- I've been receiving SP notifications about sims aging up that I didn't even know existed in the town (I keep a pretty close track of everyone)
Not sure if it's exactly related, but I haven't had any issues before this happened.

I doubt it's my mods or CC acting up, since I've had them for a while now with no issue. I recently installed the WA EP, but I haven't actually tried traveling yet, and I've also played that for a few days now without a hitch until this recent problem. My computer is a fairly new gaming laptop, so I highly doubt it's due to lacking capacity, either. Could anyone help, please?

Have you manually triggered Overwatch to Recover Missing Sims (under Immediate) or did you wait to see if she recovered on her own? You may need to do a reset on the town. If you haven't already, explaining this over on the NRaas Chatterbox might be the way to go. I've had one or two borked non-actives in the past, but not as bad as your poor gal.

Hoping that all can be recovered and your game returned to the way it was before.

I thought I had tried manually triggering it already, but apparently I hadn't - upon starting up the game and doing it, it managed to recover her (and a score of other sims who had also disappeared gone unnoticed by the automatic Overwatch, it seems)!

It took several more tries with switching households + resetting + trigger age transition in various combinations before I could manage to get her aged up right. I would guess her face was borked for some reason, because every time she was reset she'd appear with different facial features. Eventually I got a notification about "Exception of type Sims3.SimIFace.ResetException was thrown", she reset to pudding face, and I finally got her to age up into a teen.

The other glitches mentioned above still persist, however, and there seems to be some general problem with aging up and people's faces resetting when failing to do that, so I might still need to reset my town. (I assume through MC > Town > Reset Everything? Or is there some other method?) Or would it be a better idea just to load my sims into a new game, period?