I'm also having this issue, on top of not being able to even talk to them if they show up at all. Sometimes I get the success pop up and nobody shows up at all (and I'm looking everywhere, paused and unpaused). Sometimes when I do find them they're not even an NPC I can interact with. I've gotten a 4 star celebrity so I couldn't do anything but ask for the sugar skull, which of course failed. Just now I finally found the person as she entered the neighborhood, who then beelined across the square (I'm in the Arts neighborhood of City Living), and immediately disappeared. My character was doing nothing and had the interaction queued, but she never moved and the NPC despawned. I couldn't even reset the Celebrator with shift click. Failing to even get them to show up happens 5/7 nights. I've been trying this between two worlds, about 4 years in-game with one week seasons, and I only have a few skulls because of this. I didn't think it would be this hard to complete this collection, it's beyond frustrating.
Editing to add, I've been able to interact with the NPCs in this neighborhood before, so I know it's not the world. The two times summoning has been successful I've been able to get a skull from them. But they shouldn't just spawn and then immediately leave.
I haven't had one spawn in a VERY long time so I thought it was a limited thing. How do I get one to show up? I have the interaction at the grave, but then nothing happens...
