Multiplayer with 2-3 players. There were 2 Engineer NPCs in the dungeon when we "saved" them, in adjacent rooms from each other. They of course died rather quickly in the dungeon. I didn't think much of it as I knew she should respawn eventually.
But hasn't, and I bet we've put in a good 10+ hours of gameplay since then. Maybe even more.
We keep making houses, and duplicate NPC's keep moving in instead of the Engineer. We have 2 goblin tinkerers, and 2 nurses. I killed one of the nurses with lava to see if that would help the engineer spawn, but it has not.
Plus, there is 1 other "house" on the far side of the map by the dungeon we occasionally use as a spawn point w/ a bed. As far as I can tell, that house has never been occupied.
If I bring up the NPC/social menu, I can see that the Engineer is not listed (and so not "living" somewhere on the map other than our home base).
Any idea how to get the Engineer back? The server is running TDSM 1.1.2 on a Linux box using Mono. This is the first multiplayer server I've run, and there is not much on TDSM on the web anymore (their site, tdsm.org, is no longer up). I've restarted the server to no avail.
UPDATE: We are currently at 1 NPC per NPC type, except no Engineer, and we have 6 (yes, six) Goblin Tinkerers.