"Also, try a cup of powdered dishwasher soap in the tub of the washer"

I've been using Front Loaders for almost 20 years. Long before they became "popular" and - for the most part - affordable.

I had odour problems - and imbalance issues - even with my first front loader. A German made AEG unit. And the distributor (and manufacturer) both recommended running a "hot" cycle with a cup of powdered dishwasher detergent in it about once a month. Cleans and disinfects the tub and seals, and, it cleans out any residue built up in the tub, on the drum, etc.(Dishwasher detergents usually contain bleach.)

NOTE: The European machines are 220 volt and "hot" means cranking them up to 95°C. North American models don't go that high but they do have a "sanitary" cycle on them that heats the water to at least 70°C. USE IT. You need it to kill the bacteria.

Cheers!