Well, there's a thread about it:
https://steamcommunity.com/app/17167...777/?l=english
People are saying it's happened to them. But lots of others saying the puzzles are made from the rings they give you and they're all solvable. Everybody is asking for a pic of an unsolvable puzzle, but there hasn't been one yet. I haven't had it happen to me, and I've done many hundreds of locks. With this game, who knows. Could be another a bug.