I have been farming Cobalt nodes in Borean Tundra and I keep running into the same issue. I get the point for hitting the node, but I do not receive any cobalt. The in game message says corpse is being looted by another player.
Someone might have only took the cobalt and left the other items.
Bags full does it for me to leave the node there.
Not got that error yet, but not in Northern yet.