It seemed like some levels weren't accepting legitimate horizontal 100s (or that the 0s couldn't be exchanged). Maybe vertical too; I don't recall for certain.
If I'm not misunderstanding you, that's an intended design decision. The puzzle it's not just to form a 100, but to form a 100 and making it to the exit. Some levels were designed with that premise: tricking the player into forming a 100 in a way that makes the exit unreachable.
