Very, Very Strange Water Softner issue

I have a Fleck water softner. I've run into a very strange issue with it. It worked great for about two years then all of a sudden whenever I use my garden hose, the softner stops working. I mean it instantly stops softning and has to be regened a number of times before it begins working again.

I put a check valve in before the softner (the hose is before the softner), I've changed the resin, replaced the head components, cleaned everything...nothing seems to work.

I've spoken to every expert that would listen, including Fleck techs, and no one has heard if anything like this.

Has anyone run into anything similar?