Okay, actually no, I haven't figured it out yet.
Like right now, I've got this dwarf Led I'm trying to draft. In Dwarf Therapist he's got the military skills I'm looking for, he's a gemsetter, and his current job is collecting clay. Not only doesn't he appear as a recruitment candidate, he doesn't appear in my unit list at all. Nobody in the gemcutting or jewelry profession, and nobody currently collecting clay in my unit list matches the characteristics of the Led I'm looking at in Dwarf Therapist, which seems to preclude a mismatch between his listed name with Therapist. They also show no signs of being a vampire. I've changed his nickname in Therapist to include numbers, and he still doesn't show up in any unit list.
I've pored over the boundaries of the map and don't see anything that looks like a migrant block, or any unaccounted for citizens standing around like they're bugged migrants.
What could the issue possibly be? I guess I could go over each and every unit within DF itself looking for his skillset but at that point I'd probably just say screw it and learn to ignore these units for assignments, because that particular portion of the interface crosses well over my line of tolerance for clunky.
*edit* The one and only unaccounted for detail that I can see right now is that one of the entries in his skillset in Therapist is "Novice UNKNOWN."
*edit edit* Okay another discrepancy. Therapist lists one more very skilled (Master) gemsetter alongside Led, but in the DF unit list itself the only gemsetter is listed as only being "Adequate," and his name isn't the same as it is in Therapist.
I'm more and more thinking these are Therapist bugs, not DF ones. And that would suck. Because I depend a lot on Therapist and have zero interest in using the native interface to deal with skills and jobs.
Okay. One more discovery after going over the entire map tile by tile. Donno how I missed it the first time. In the upper left corner of the map there is one tile of "clay wall" with up ramps surrounding it. On the z-level above the up ramps lead to it just says "siltstone" on that tile. I can't manipulate it in any way, can't smooth it, can't mine/channel it (obviously since it's at the edge of the map,) can't do anything to it. The "siltstone" above is listed as outside/light, the "clay wall" below is (still on the actual ground) is listed as subterranean/dark. Is there a dfhack I can use to delete the wall on that tile or somehow clear what looks to be an unknown obstruction?
It looks like this, in the very corner of the map, where X is the clay wall and * are the ramps. This is on the primary outside ground level.
One Z-level up it is exactly the same only the clay wall is just "siltstone," not "siltstone wall" or "floor" or whatever, and it's surrounded by empty space/air.