Diagnosis
You're likely using the wrong brew size. The Over Ice setting is programmed to brew a stronger, smaller volume directly onto ice, but only with the specific carafe positions.
How to Fix It
For the Over Ice function to work correctly, you must use the 6oz or 12oz cup size setting. Fill your cup with ice first, select Over Ice, then choose 6oz or 12oz. Do not use the Carafe setting with Over Ice.
If That Didn't Work
The machine might not be recognizing the carafe position sensor correctly. Clean the sensor window (a small plastic nub) on the warming plate and the corresponding spot on the carafe with a damp cloth.
Heads Up
The coffee brews hot—it's concentrated to account for dilution. Use a full cup of ice. If you use less ice, you'll get watery, lukewarm coffee.