Dealing with invisible townie sims is one thing I've had a hard time with. When you don't know who it is, it's hard to reset them. For quite some time, after I got NRaas mods, I used Master Controller to reset the whole town every night. While I was doing that, I had no invisible townies, but it caused other problems. So, I started just resetting all the sims in town every night, right after Overwatch finished its nightly maintenance. That worked better, but was time-consuming to do. I've tried Overwatch repeatedly, with the fix invisible sims command, but it never fixed the ones on the lot where I was. I've finally found a solution that works for me every time, and isn't such a pain as the other ways I tried. When I see evidence of an invisible sim, I click on the ground of the lot and choose Master Controller > sim > basic > outfit, then when I get the panel to choose from all the sims on the lot at the time, I choose all of the ones I hadn't seen, or didn't remember seeing, and select the everyday outfit.
Sometimes it's easier than that. If I see a pair of skates going around the skating rink, all I have to do is click on the skates and change the outfit. LOL!