If there is actual ozone residual in the pool, then it will measure as Combined Chlorine (CC). This is because ozone doesn't directly react with DPD for the FC portion of the test (at least not much), but it most certainly oxidizes iodide to iodine when you add the R-0003 reagent during the CC part of the test.

Get rid of your ozonator. It's pointless in an outdoor residential low-bather load pool exposed to sunlight.