DIAGNOSIS This is a water flow issue. Not enough water is entering the freezing tray during the fill cycle.
FIX Clean the water filter. Unplug the unit. The filter is a small cylindrical screen inside the water inlet port where the rear reservoir connects. Remove it and rinse under hot water, scrubbing with a soft brush to remove scale.
IF THAT DIDN'T WORK The fill time might be too short due to a failing water level sensor. There's no user adjustment for this. The sensor is a float switch in the rear tank. Ensure it moves freely and isn't stuck.
HEADS UP Consistently thin ice can also be caused by an ambient room temperature above 80°F. The unit can't freeze fast enough. Move it to a cooler location.