I have this shit with sword smithy on Skellige lol. First of all when he appears i am unable to talk to him. When i medidate hi might disappear and then i just have to go away a bit then turn arround and he appears from nowhere lol.This issue also happens with some other smithies but only those who make swords for some reason. Mostly you just unable to talk to them they reply like any other decorative Npc's so i have to meditate.

Yep, there are probably a few other merchants that have this kind of thing going on too. The alchemist sitting outside the Cunny of the Goose near Novigrad also has some weirdness, which others have reported.

And just found the Enhanced Northern Wind recipe has the same problem as the Enhanced Moon Dust recipe. There are probably a few more of these recipe bugs I haven't found yet as well.

Hopefully patch 1.05 fixes stuff like this (including the mutagen bug Eolen pointed out), which aren't exactly "game-breaking," but are still pretty huge/annoying glitches. Since I doubt the devs are reading these forums for bug reports, I emailed the bug list to the technical support contact a couple days ago, and the support guy responded saying they're currently working on some of them (didn't say which), and he'd send the list to them so they could review the rest. We'll see!