Can you help me figure out how to pry the knob off of my glass topped stove?

I have a glass topped electric range. It’s about five years old. Every few months, I take the knobs off to wash them with soapy warm water. They’re usually firm to take off, and a good strong grip and pulling them upwards gets them off. There’s a metal shaft that the plastic knob goes onto. I should mention that i don’t do a whole lot of cooking on the stove, so it doesn’t get particularly greasy or anything.

The other day, I took three knobs off and the fourth knob just won’t come off for anything. It’s for the burner that I use primarily (just out of habit). I am pulling it straight up, wrestling with it, using a jar opener (rubber disk shape to help grip), everything and yet nothing works. I don’t want to pry it with a screwdriver or other metal instrument because I am afraid to break the glass.

Do you have any recommendations for what might help to get it off?