Diagnosis
Persistent mildew smell is caused by biofilm in hidden areas. The primary reservoir is the rubber door boot gasket. Mold grows in the folds and the drain trough.
How to Fix It
Run a manual clean cycle with the washer empty. Set the cycle selector to Clean Washer. Set the temperature to Sanitize. Add 1 cup of bleach to the detergent dispenser. After the cycle, wipe the entire door boot, inside and under the folds, with a 10:1 water/bleach solution. Leave the door and detergent dispenser open after every wash.
If That Didn't Work
Check the drain pump filter housing and the small drain hose from the boot to the pump. These can trap stagnant water and debris. Clean them as part of the F-01 drain procedure.
Heads Up
Using too much HE detergent or fabric softener creates excess suds that don't fully rinse, feeding mold growth. Use no more than 2 tablespoons of HE detergent.