Near the end game and have yet to come across the Superior recipes for Draconid, Cursed and Necrophage oil. Also missing Superior Northern Wind.

Read about a bug that can prevent certain Superiors from appearing in the game. Any known workarounds? I'm afraid of having to resort to mods to get the four Superiors that i'm missing.

There's a dwarf herbalist outside east of Oxenfurth. you have to find his hut, not too far from the bridge. If he don't have it, try the druid Gremis, in Skeilege where coronation happened in "KIngs Gambit", but, you have to do the Advance Alchemy quest with him before you can unlock his merchandise. Sometimes, doing free explorations, contract, treasure hunts, side quest, and in the main quest itself, you will be granted these formulas as well,

He's a Halfling, not a Dwarf.

I've went to both the Halfling outside of Oxenfurt and Gremist and nothing.

The recipe drops are random if not bought off the merchants Again, I'm near the end game and statistically, the 4 Superior's i've been missing should have dropped by now.

Apparently i'm not the only one experiencing this. There might be a recipe drop bug.

As far as I have experienced it, every recipe gets placed along the exploration of the world - so if one misses some containers/chests, they may be unobtainable somewhere else. I have found a chest in the canals of Novigrad which I did not see during my first visit - and found something nice inside.