Thanks for playing!
I'm glad you had fun despite how the zipper works.
It actually has some feedback, it should shake and play a sound (a gun cocking sound actually lol). Maybe it got glitched or maybe this isn't obvious enough.
But I also got this feedback from testing before release, that the stuck mechanic can be confusing. Maybe I could make it work better, but I think it's not worth confusing the player over this.