I gave it a try and ran into a situation where the 8 of hearts was the open card at the bottom of a column, and I had a 7 of spades sitting alone in another column, and when I tried to move the 7 to the 8, it refused to let me do it. It's been forever since I've played Klondike, and I've never looked up the official rules, so I'm not sure if there's a rule I'm unaware of or if it's a bug.
In the same game, I just ran into another one where I turned over the six of diamonds from the stock pile, and when I tried to move it onto the 7 of spades, it also refused that move.