Their behavior is spot on but those eggs definitely aren't fertilized.
It looks like there is an HOB filter right above their breeding site. My only thought is that is creating a current that is making it hard for him to fertilize them.
I've had Oscars pair off several times but to my recollection I've only had free swimming from from one of those pairings and I've seen others report similar results. I suspect infertile Oscars are a fairly common thing.
Whether you ever get fry out of them or not, it's beautiful watching their breeding behavior.
Watch them for aggression toward one another. Sometimes after repeated failures they get frustrated and take it out on each other.