Diagnosis
Moisture or grease has seeped under the capacitive touch panel. This disrupts the electrical field. Common from steam or cleaning sprays.
How to Fix It
Unplug the unit. Use a slightly damp (not wet) microfiber cloth to clean the screen. Dry it immediately with another cloth. Do not use spray cleaners directly on it. Let it sit unplugged for 24 hours in a dry place to let any internal moisture evaporate.
If That Didn't Work
The touch panel flex cable might be loose where it connects to the main board. This requires disassembly to check. The control panel itself could also be failing.
Heads Up
Never steam-clean the control panel. Wipe only when cool and unplugged. A persistent fault means the sealed touch panel assembly likely needs replacement.