YES!!!! My cooktop is about eleven yrs old and I have the same problem. It's by guess & by golly when I use my settings. The first liquid to remove the paint was Simple Green. After cleaning one knob, I stopped. But since just about any cleaner or even a miracle cloth might do it. I haven't contacted DCS/Fisher Paykel, but I assume we're out of luck!

It has to do with cooking oils. Some types of oils act like a solvent and soften the paint.

Most companies test against most normal cooking oils like vegatable, canola, and most animal fats but every once in a while a "new" oil will become popular that wasn't tested.

At least I'm glad to know that I am not the only one with this problem. As far as an oil dissolving the paint I don't think that would be the problem because I don't use any unusual or new kind of oil. I should call the mfr or go to the shop that sells parts for the DCS cooktop.

I have a new Bosch range and about the third time using it I noticed on of the knobs got all gummy so I grabbed a wet paper towel to clean it and the paint rubbed right off. I called Bosch who acknowledged the issue and overnighted new knobs which are clearly a different finish. Hope these last more than a week!

All this to say, there's a chance DCS knows about the problem, has corrected it, and will send you new knobs. Worth a call, anyway.

I agree, I never fry and when sauteing I use olive oil. It's not the type of oil. My cooktop is 11 yrs old. I doubt they have replacements, but even if they do, it will be hell getting that portion of the knob off of the cooktop without scratching the heck out of it!
Update: just tried to unscrew the escution plate ( that used to hold the markings) and I dropped a screw in to an abyss. The two screws hold in a U shaped metal plate backing which dropped into an inaccessible space. I was able to retrieve it and screw one side back on which will anchor it, the other screw is lost, likely forever.