I actually had this exact problem and I thought maybe something was wrong with my sim itself as I do use cc, sim had a child and I also have the same problem with her too
Another thing I found during the same save is for some reason sometimes I can't preform romance interactions with other teens, more specifically I could only flirt and that's it, no other options whatsoever
I had this problem too...one of my teen sim was asked out for a party or something that night (the call usually comes in the afternoon) but when I was trying to sneak out in the evening, there was no option. I clicked the new window, the doors, the floor ouside the house, the ground. Nothing was there.
After many unsuccessful tries, I found out why: The (in game) time window when you as player have the option to sneak out after the call is incredibly small. I had to basically pause the game immediately after the call (on game speed one) and while it's paused click the ground outside the house (not the window, not any kind of "room" outside the house or even floor with tiles on it) - simple grass. Then I had the option to sneak out. If that lined up action to sneak out gets cancelled for whatever reason (your sim takes too long to actually do it, your sim is clumsy, has a fear related moodlet that cancels all lined up actions....), you will not be able to sneak out as the option on the ground has already disappeared.
If the room door is locked, your sim will exit through the window autonomously - just as any NPC enters your house through them if you don't invite them in at the front door (so remember to lock them for everyone but household sims).
