I can't jump above the first cliff, I need to use all three stumps to jump to the next area. I found out to use Z before it told me because I couldn't figure out if there was a trick or not.
It should be fixed now. Thanks for the comment! I tested it for several hours today and everything was fine, but you are right. When I tried to play on my laptop I couldn't jump high enough, weird. If you could, please inform me if it's also fixed for you. Cheers!