I found the game very enjoyable to play! The scales + hourgalss mechanics are a bit confusing at first, but quite easy to figure out. I didn't have any issues with controls and didn't get stuck anywhere.
It's a bit weird that some enemies get their state reset with hourglass but some don't (maybe I missed something). I think hourglass could shine if there were moving or disappearing platforms, but as of right now, it's just for saving some health or as an alternative to scales when they're not ready.
Maybe a healing ability could replace the hourglass, and if you're using healing too much, some enemies could steal some of your healing? Think of enemy scales but not for damage, but for healing. Just sharing some ideas that I had while playing...
Overall, I liked the game! Great job!