It seems that since the last update a problem has cropped up where the 2nd to last quest marker moves around the map. For instance: I have a side quest to kill ghouls for the settlers of Sanctuary Hills. I did that, and the quest marker for "report your success to the settlers" will not go to Sanctuary Hills. If I do go to where the marker is, then it goes somewhere else on the map and this just continues. I now have a second quest with the same problem. I rescued a kidnap victim for Tenpines and cannot report my success as the marker is always moving.

Do you have supply lines and provisioners?

When that happens to me it's because the provisioner is the settler that I have to report to and they are walking the caravan routes.

Consequently I have to chase them down.

Depending on your respective locations it can be a matter of looking at the supply route in the pipboy and making a determination of where they might be by the time you get there.

That makes total sense, I'll check that out thanks!