The title says it all.
My Sim called a friend before midnight, the car came at 1 AM, and he never returned. They normally return by 4 AM-ish, but it was long daylight and still nothing. He didn't run away because he has a good relationship with his family. The "sneak out" want never got satisfied, he was never shown as snuck out and he never got the "get busted" or "get caught sneaking out" fear.

I took out my entire Downloads folder with all my custom content. Didn't help. When he snuck out, he never returned, had to quit without saving. I tried playing in the debug mode, but there was no error message, nothing. I checked my pedestrian portals and they all seem fine. I entered a different household and had another teen sneak out - and she returned! It must be something with the lot, but apparently not the portals. The lot is a home business. Could it be the cause?
When I chose "Force Error on all" on the batbox, he returned, standing by the house. So I can get him back - but there's obviously some kind of a problem somewhere. Anyone?

Thank you for your help!

Tried reporting to cops? There's an interaction on the phone.

I think you'll need 'retrieve missing sim' on the batbox for that - sounds like the snuck out token didn't get set properly.

I found out it isn't the lot - his sister sneaked out and returned without a problem. It must be the boy, and yes, it indeed looks like the token cannot be assigned properly. But "retrieve missing sim" on the batbox did nothing. I had to "Force errors on off world" for him to return. I have no idea what is causing this. And no, I can't report him to the cops. He didn't run away, the game acts as if he was still there...

might try any summoning hack. insimenator and sim manipulator are 2.
the Tombstone of L & D (Spawn object) has something similar.
or if you have Apartment Life; you might make some household member a witch/warlock then use the summoning spell.

Forcing off world means he was just outside the zone, for whatever reason, he just couldn't get back on his own. It's probably just one of those weird, random glitches with no explanations, at least he's back now. (:

Yeah, my problem isn't getting him back... my problem is I cannot satisfy his "sneak out" want
No, seriously, most of all I just hate when glitches happen for no obvious reason and I don't know how to fix them... seems like sneaking out is going to be an activity left exclusively for his sister. Which, honestly, sucks. All my teenagers sneak out every now and then...

with the testingcheatsenabled cheat, you might Ctrl-click on the Want.

or might try again another night.

Anytime there is something different going on that may not have the results I prefer, I just save prior to whatever it is going on. For sneaking out, I would save about a sim hour before 1am which is the usual sneak out time. If something goes wrong, then I can exit the lot without saving and don't have to deal with glitches etc.. I agree, glitches often make no sense. (:

I also save the game very often, so the first time this happened I just exited without saving, hoping it was a one-time thing. But it kept repeating. I did try to get him sneak out like 6 times, never worked, and I'm tired of trying. It's apparently not going to just fix itself. I just want him to be able to sneak out normally, like any other teenager in that neighborhood... But I'm out of ideas.

How about asking permission to go out? Have you tried to see if that works? Not exactly the same, but similar, a teen going off at night with friends.

If it really bothered me and nothing else helped, I'd probably try moving the family out of the lot and then move them back in.

not entirely sure, but there might be some hack or Spawn object that could force a "sneak out".
I have not yet seen either.

I didn't really find any mod like that.

another possible solution might be to "replace" the teen with a cloned version.
one way to clone a character is the export option in SimPE's Sim Surgery. the neighorhood's file would need to be opened.
once the cloned version is made, you might either make the former version a townie type or kill him. then add the new version to the household.

I don't really want to replace him with a clone... the family relationships, the memories, going through all that in SimPe... no. He's going to become an adult eventually anyway and then all of this doesn't matter anymore - if it's really just a glitch. I have no idea what caused it. When I was trying to look up a solution I found out more threads where people described that exactly the same thing happened to them. But they were satisfied with getting the Sim back and never got to what had caused it or how to prevent it... I wish I knew.

Try rerolling his wants with insimenator or sim blender? That at least might get rid of the want!

Do you have NoSimLoaded? It could perhaps fix this. It seems this might be related to Off World Loiterers or something like that (which mod fixes that again? Batbox or the Teleport Cat from Simlogical?)

I do have NoSimLoaded in my game already. No Teleport Cat though. I thought it works the same as the shrub, only for AL - it has other functions than just the teleporter?