Like many patented cultivars, they’re clones of a sport. Grow Braeburn apple seeds and most of the plants won’t look anything like the original. Roses too.
Cannabis doesn’t work this way. Everything is very close, genetically speaking. Some plants are naturally less fertile, I guess. I’ve encountered clones that are nearly sterile. But they’ll still make a few seeds, and I’m sure the next generation would probably be just fine. You could find a sterile clone and try to patent it, but I doubt it’d somehow be leaps and bounds better than other clones that freely make seed.
As to why you’re having difficulty, IDK, some plants are very hard to grow from seed, especially ones with tubers/rhizomes Daffodils, Cryptocoryne, etc.
If anyone’s got the specifics on what all these Cannabis breeders allegedly “been doing since the 80’s” to “protect their interests against filial generations” I am all ears.