If the waste pipe goes into its own, dedicated, vertical stand-pipe,with a trap at the bottom before it joins the drain, and with the flexible waste hose just tucked a couple of inches into the stand-pipe, that removes the most common cause.
If you have cleaned out any residue of rotting food from the filters and arms, that removes the next.
If the supply pipe somes from the mains, so there can be no fragments of drowned and decomposing mouse from the tank or pipes, that removes a less common cause.
If the heater is bringing the water to full temperature, that should kill most organisms inside. And if the softener is well-charged with salt and working properly there should be no scale to catch food traces. If you are using a good brand of detergent tablet, there should be no foam to prevent the pump from washing away all food traces. You must not let washing-up liquid get inside the dishwasher.
I've run out of ideas.
You could try a "dishwasher freshen up" bottle. You put the whole bottle into the dishwasher (you don't tip the contents out)
You can make sure the door is left slightly open after use to prevent it being damp enough to support mould or bacteria.
If you can post pics of the pipes, that might spark some ideas.
Check inside the cabinet during a wash to see that the pump is emptying all the dirty water at the end of each wash and rinse,and that there are no upright vessels (pans or mugs) holding used water,and that it is unbearably hot during the wash and final rinse.