I've had 4 or 5 instances where a 'use a lantern' quest has failed to trigger. In most I was sure I was in the right spot. In a couple of instances having a second player with a lantern join me triggered it - for the others I was solo or it made no difference.
I can only assume the detection radius is so small you cannot trigger it, or there is something up with the trigger event itself. Only option has been to cancel the quest.
Anyone else experienced this?
