After asking for a mission from the starter NPC after doing their first mission.
^ The picture pretty much explains everything.
I had this happen to me too, with two different NPCs. I thought I was able to clear it by asking for another mission with my first NPC, but the second NPC it didn’t seem to work, but the NULL mission is not in my mission log anymore, so not sure.
got the same thing happening at both the center and the farm.
Just happened to me as well. v. 6516
I got this from an NPC and accepted two of them to try and see if it’d help get rid of them. But it didn’t. After the NPC died it said I failed two NULL missions.