Oscars as most cichlids exhibit spectacular parental care. The first spawn or two often fails from fungused eggs which the parents don't pick off. The fungus spreads, then they just eat it all. Most cichlids spawn every 3 weeks. Fry should be removed 1-2 weeks after entering the free swimming stage. The earlier you remove them, the more survivors you have...however they grow much faster when with the parents.
I personally think conditioning cichlids with special foods is nonsense. (not to say you shouldn't be feeding high quality pellets and worms or fillets as a supplement) If your fish eagerly eat and the water quality is good, they'll spawn. A temperature swing from the mid 70's to 82-86 is what makes a fish spawn, or at least in my experience.
Your oscars are too small to spawn, I had a pair that acted the same way, never got anything. I breed all different types of cichlids and fish, some spawn young, some not until much later. I've never seen or heard of an oscar spawning under 11". You might have a chance when they're both 12"+??, who knows, time will tell.
BTW, Welcome to MFK!!