"Too far away to loot this corpse."
 

When the mob dies at a large distance from you, you may observe the corpse in a location different than someone who was nearer when the mob died. If you try to loot the corpse in this scenario, you'll get the message "Too far away to loot this corpse".

If you relog, the mob's corpse will appear in the correct location, allowing you to loot the corpse.