Re: when the trusty Tide and bleach isn't working.....
We had that problem with Tide, and I find it in the supposedly clean FSOT diapers I buy from Tide households. Switching to Country Save plus a bit of Bac-Out, or Biokleen with enzymes, have served us much better. Whenever I wash a Tide user's diaper in Country Save, it starts revealing a lot of stink as it peels off the built up Tide fragrance.
If you want to stick with the Tide, increase the amount you're using or add a Tablespoon of washing soda. Bleaching more or soaking in oxiclean will really shorten the life of your diapers. Using bleach and oxiclean together creates toxic fumes.
Doesn't sound like vinegar would be helpful for you.
I've never washed our washing machine ...