DIAGNOSIS The taste is from volatile organic compounds (VOCs) in new plastic parts or from stagnant water sitting in the internal lines between uses. It's not harmful but is unpleasant.
FIX Perform a accelerated seasoning process. Unplug and empty the unit. Make a baking soda solution: 1 tablespoon of baking soda per gallon of warm water. Fill the reservoir to MAX. Let it sit, with the lid open, for 1 hour. Then, plug it in and run it through three complete ice-making cycles, discarding the ice each time. Use fresh water for each new reservoir fill. This neutralizes odors better than vinegar alone.
IF THAT DIDN'T WORK The carbon filter (if your model has one in the lid or reservoir) might be saturated or missing. Check for a small black filter cartridge and replace it or ensure it's installed correctly.
HEADS UP For long-term storage, you must run a vinegar cleaning cycle, dry the interior completely, and store with the lid open. Storing it with any moisture sealed inside will guarantee a mildew smell next time.