My house has 3/4 inch particleboard over 3/4 inch plywood for the subfloors. This stuff ain't gittin' the job done. My floor has all sorts of ripples and soft spots.
I can only assume that the particle board adds little to nothing in the way of structure or strength (it crumbles in the hand when I pry it up) and the single sheet of plywood isn't enough on its own. As I go through the house remodeling, I've been pulling up the particle board and replacing it with an additional sheet of proper plywood. It seems to make a big difference. The floors I've redone feel solid, the ones I haven't done don't.
Anyway, I would suggest that if you have the subfloor exposed, you take the opportunity to put some real wood down. It's cheap and easy and quick, and you won't have to wonder whether your vinyl will stick to it.