I can travel to the lot stuck-sim is on, and also add her to a group, but from the moment I let my active sim travel somewhere else it gives this screen where you can select who's going to travel with you. Stuck-sim doesn't show up in that list at all even though she is there, in a group, or even in a club. Basically any interaction that gives you a menu to choose Sims from doesn't work: texting, calling, inviting, traveling etc...
I've tried resetting the sim multiple times but it doesn't do anything.
I added a screenshot to show what happened. My active Sim, a good friend of stuck-sim added her to a group. Next, I clicked Actions>invite (to a different lot), which gave the option screen. Stuck-sim once again doesn't show up... and if I just click "ok" without adding anyone, my active Sim travels alone.
(I looked in all categories of the option screen but she's nowhere to find.)