Dek - I'm not sure what to tell you. He actually finished the sculpture right? It wasn't a gnome and he did it all the way to the end? IF so then it's an odd glitch I've never seen before. Clear the caches as per normal and hope a restart fixes it.
Yes, he finished it, I have no gnomes and he did it all the way to the end.
It isn't a game breaker, it happening to him. I will be keeping an eagle eye on Cosette though, she is the Founder and I REALLY don't want that to happen to her to be supermaxed skill.
I'm about to do the caches now.
Edit: After clearing the caches, the Motive Mobile returned from wherever it had disappeared to.
The number of stone sculptures completed by Thornton remained at zero, however.
He has now done Cosette's adult ice sculpture and the number of ice sculptures has increased by one, as has ice sculptures of sims and total sculptures. So, I'm hopeful it is all fine now. Thanks for your response, Ricalynn.
Edit II: He has now down a second stone sculpture, and it advanced from 0 to 1 so that's good, he may yet become a Master Sculptologist.
As I said, Cosette's has recorded all of her sculptures, and that's the one I'm definitely wanting to make sure I've gotten correct, as her supermax is sculpting.
Thanks again, Ricalynn.