Levelled NPCs won't respawn.

[Nihilisaurus]

I'm having troubled with levelled NPCs (the talon company ones to be specific). I've not modified them apart form changng their inventories ( on all the same npcs as vanilla the "respawn" flag is checked. I've placed these npcs in a wasteland cell (fortBannister, and the adjacent cell with the big hill). The stock respawns still work, but the ones I've placed resolutely refuse to do anything. This is annoying as they worked initially but after the first time no longer spawn mercs.