I seem to be having issues with Ed-E. He vanishes. I still have the perk and the people at Nellis AF base keep commenting on my robot problem but I have no idea where Ed-E is. Any suggestions on how to find him. I traveled back to Prim and he is not there. I assume this is a bug of some sort. I had this happen at Black mountian as well and found him stuck on a rock. I tryed to get him to follow but finally had to restart at a earlier save to get him to follow me again and off the rock.

I can think of one stick place right off.
I had an npc move past me in a narrow space, which ended up with my character stuck in a wall.
I popped the console to TCL out of te wall, but if this can affect the player, it WILL affect NPCs too.

On the PC, in the console, to Summon Ed-E (I have not upgraded my Ed-E yet, looks like there may be 4 of these, one is the broken bot):
prid 1732d1
MoveTo Player