DIAGNOSIS The touch panel film is separating from the OLED display or has developed dead spots. Moisture or physical pressure causes this.
FIX Power off the printer completely. Use a soft, dry microfiber cloth to clean the entire screen surface. Apply firm, even pressure across the screen, not just on the buttons. Power back on. The capacitive touch may recalibrate.
IF THAT DIDN'T WORK The touch panel connector on the main logic board is loose. This requires disassembling the front control panel to reseat the ribbon cable. Not recommended without experience.
HEADS UP Do not use glass cleaner or any liquid directly on the screen. Liquid can seep into the edges and permanently damage the touch sensor.