I really recommend for a clear/visible BIG mark on the terrain/title-map your char need to go so the game recognize that you did “find” the dark elf’s villager, right now i did go there and talked to every one, and moved in every terrain/title-map in their cave/base, but the game still do not let me recruit them.
Same for gnomes trade route.
Or better, change it so if you talk to ANY one of them, game mark that you did “find” them.