I have the exact same problem and have gone down the exact same rabbit hole with no real solution.

Fully disassembling (essentially uninstalling), cleaning, and sanitizing everything that touches water seems to fix it for a few cycles, but it slowly comes back over time.

The problem has followed me across states, houses, and dishwashers. I’m assuming it’s modern enzymatic detergent like you suggest.

Slightly more frustrating is that not everyone seems to smell it, or not as strongly as I seem to. It’s like dishwashers everywhere are gaslighting me.