I do humid soaks for that.
Sterilite tub with lid, one inch to 1 1/2 inches of 85 degree water with a towel/pillow case at bottom.
Let snake soak for 30 minutes, replace water let soak again for 30-40 minutes.
Shed will either be off or slide right off.
Your humidity gauge is lying, 75% humidity will give you perfect slippery sheds, not dry stuck on sheds like this
Try adding a humid hide and keep it damp, it will help your snake during it's next shed.