This is still happening and it's definitely not just vampires or teens. And it's not just dates. I recently played Strangerville and my Sim was dating the librarian NPC. Every single time he would either travel with her to the local bar, or go to the bar and then invite her to hang out from there, she'd arrive and then immediately leave. If my sims invite the NPC sim to their house and hang out there, they'll stay for a while, but any public lot seems to cause the NPC sim to leave immediately after arriving. Very frustrating.
I'm also experiencing this problem with my sim that lives in Strangerville. Are the NPCs here not date-able because of the possibility of infection? Just a thought. I'm having trouble with Jess Sigworth (infected), Erwin Preis (not infected, manager of the curio shop), and Don Lothario (not infected, nonresident, but bartender at 8 Bells.)
I have successfully dated Sims from StrangerVille as recently as today, including Jess Sigworth, Meredith Roswell, Alice Martin, and Leslie Holland. Gold dates for all of them. I think Jess and Meredith are currently infected but that hasn't been a problem.
I found my problem, don't know if it will help anyone else, but just in case...
The sim trying to date was an alien (from GTW) and I had used MCC to add the "hidden_isalienpolinator" trait. I thought this would enable her to impregnate a male and have a full alien baby, but it didn't. What it DID do (apparently) was to signal the game that she was a hidden NPC, and ineligible for most, if not all social events. It was as if she wasn't there at all. When I removed the trait, everything went back to normal, or as normal as things get in Strangerville, anyway.
