A little bit of background:
I have a fortress where the ground has been de-ramped and the edges floored over to restrict access. Naturally, trade liaisons like to appear in these cut-off areas, and one day I got sick of having to deal with them and left them all to stand outside while I got on with things (I had invasions turned off for this). Cut to a few years later, and I decide to hold all the meetings and send them all on their way before reallowing invasions. The human, elf and knockgoblin representatives all had a meeting with my leader, but the dwarven representative is MIA. S/he's not in the unit list, listed anywhere in Dwarf Companion, and didn't turn up with the dwarves the autumn after the other three meetings. I can get stones and gems and steel off the knockgoblins, whom I modded in for use by Mountainhomes, but my home civ had pretty much everything. I made a backup, abandoned, reembarked with the original civ, and got a liaison. I don't know what Legends says (if anything, which seems unlikely) as the game hangs whenever I select it.
There's probably very little I can do about it short of restarting, but has anybody else had this problem? What makes it even worse is that I knew that it was possible to selectively and remotely cut off access with a hatch, but didn't do so. Next time, I'll use that exploit.