Diagnosis
If the fan is running but no water is collecting, the most common culprit is a frozen evaporator coil. This happens in cooler rooms (below about 65°F) or if the filter is clogged.
How to Fix It
Step 1: Turn the unit off. Step 2: Remove and check the air filter—clean it if it's dirty. Step 3: Unplug the dehumidifier and let it sit for several hours to let the ice melt completely. Step 4: Plug it back in and set it to a higher target humidity (like 60%) and use Continuous mode. Make sure the room temperature is above 65°F. It should start collecting water within a few hours.
If That Didn't Work
The humidity sensor might be out of calibration. Try running it in Continuous mode (the water drop icon) instead of a target % mode. If it collects water in Continuous but not in Smart mode, the sensor is likely the issue.
Heads Up
In a cool basement, these high-capacity units can freeze up regularly. Using the "Continuous" mode instead of a very low humidity setting can help prevent it, as the compressor cycles less aggressively.