I do not claim to know what will work, but if the problem were mine, I'd spray the metal parts heavily with WD-40 and let them sit for a day or so. Maybe you'll notice a little "give" and can repeat the procedure. Good luck.

Buy a new knob or move that into a closet/ guest room. The way the metal bezel is formed onto the glass is pretty likely to break the glass if you try to remove.

Sometimes baking soda with a bit of water paste on than rub with a 1/2 lemon Use the lemon like a sponge.  Worked on a few items for me. A