Right, I've looked into the itch app and, from what I can see, if you have downloaded the demo, it will not let you then download the full game and vice versa. I found I had to uninstall the demo in order to install the full version. I'm not sure if this is how it should be working, but this is what my tests found (unless I was completely missing something - which is possible) . If this isn't related to the problem you've been having, could I ask you send a screenshot of the problem to firstname.lastname@example.org , please, and I will investigate further.
As for the skip option and rollback functions, I've created a new build of the game with rollback enabled and the quick menu (with skip button) available at the bottom of the screen. Please let me know if you would prefer this one and I will get it uploaded.