Wow, it sounds like Instant Boot changed some Windows settings regarding power options (which includes Sleep and Hibernation) that are not readily available in Windows. It sounds like you followed the correct procedure for turning it off. There is very little documentation about it AFAIK, which does not help.
I don't know what settings Instant Boot changes, or if you can fix them on your own. One way to check and hopefully reset things is with the Windows command line program, powercfg. That is run from an Administrator level command prompt, the "cmd" window. You'll need to familiarize yourself with this command, it has many options and can show you the current state of the Windows power options, and should allow you to reset them.