I was on an regular railroad radiant quest, somervile place, killing ghouls at an location where I know an shotcut to boss, fast travel to location, jump up the shortcut, sneak in and kill boss ghoul.

Ok back to somervile, quest marker not at location, four settlers, ask all of them they just offer to trade items.

Look at quest marker who is north east of me, fast travel to location, marker continues to move north east, trying to intercept but not far enough. Do an quicksave and reload after next jump missed and I got close.

As I suspected it was an provisjoner, quest delivered, return to Preston.

Now this rases two issues, first why use an travelign npc as questgiver ??

Secondary why does an provisjoner going from Sommervile to the castle go by Cambridge police station?

Yes, yes he see an BoS scribe at the location I don't care as long as he does his work.

Its the second time it happened to me, first time I could not find questgiver to start quest so it failed, but remember the weird location of marker who I ignored. now 2 MM quest later and it repeats.

I had this too. Got a Quest at Sanctuary but the Questgiver was stuck in Water near Quincy after i finished it.