Just had an experience where I joined a friend's game. He had just completed a convoy tagging mission. The convoy was still sitting there and available as a mission for me, which is fine, but I stupidly went to tag it before grabbing the mission. So the first issue is that it let me tag a convoy without picking up the mission. The second issue is that I could then pick up the mission, but couldn't re-tag the convoy, or get credit for the existing tag. This persisted through leaving the game and rejoining. I even destroyed the convoy truck to try to get the mission to go away, but it's still sitting there, trying to get me to pick up a convoy mission to tag an untaggable, destroyed truck.