So, this is my second play-through. In my first game, after unlocking everything to do with Bunker Hill and becoming allied, the caravan traders stopped appearing anywhere. Trashcan Carla, Lucas, etc. I have no mods affecting them at all, or Bunker Hill, and could not find any answers no matter where I looked. ('net, forums, etc.)
I eventually gave up and just dealt with it. Now, on my second go 'round, I did a quest for Kessler, which did not ally me with the settlement, but did unlock trading posts. I didn't care about either this time, but once again the trader caravans have disappeared! I know they aren't dead, I could console Trashcan Carla to my player in Sanctuary, and even interact with her, and then she rushed away. I've played and waited for more than long enough for any of them to show up, but they aren't anywhere that I can find.
I could find no bug info on this, does anyone have any ideas to get them back on track? It's really annoying and changes the 'feel' of the game.
Edit: No trading post mods either, and no trader mods.