If a change hasn't been made, the listing is indeed in error! I tried to run the original conventional Hogwart's locomotive on O31, it was a no-go! I even took a little material off the cylinders where the pilot hit them, but it still derailed. If you take the pilot off, it does O31 great. They barely make O36, but they do make it.
I don't know if the new one is any different, I haven't looked at one yet.