When you said you wash in 50/50 vinegar/water, and then soak for 15-30 minutes, are you soaking the parts in the vinegar/water mix, or soaking them in water or something else? And do you wash the parts in some sort of cleanser first?
I take a throw away container put in all the silicon pieces.
I then add hot water and then add about the same amount of white vinegar, and rub the parts a little to get the cleaning going.
I then put on a cover and soak it 10 to 30 minutes depending on how bad the mask is. Normally for me it starts feeling squeaky at about 15.
I give them hand washing in the vinegar/water mix making sure there are no greasy spots.
I then take the parts out and give them a really good rinse, again going over the silicon to get any greasy feeling spots off, normally there aren't any at this point.
I then lay the parts out on a clean white baking towel or paper towel if my good baking towels are dirty and let them air dry.
The plastic molded parts I clean with Dawn and good them a good once over and rinse.
Then lay those out to dry. When all parts are dry I reassemble the mask.
The mask comes out very clean and works just like new. With little to no smell.
Small tip for anyone who gets a scaley build up on the heating plate of some of the older style heated humidifiers. Soak the scaled up heating plate in pure white vinegar for 10 and come back and wipe the scale off. If not completely clean soak for another 10 minutes and wipe the next layer off. By the time your done the heating plate will be pristine. Rinse it well let dry and your good to go. Works for home humidifiers too.