Guild Wars 2

We tested in Devourer Burrow and in Ghost Wolf Run – as long as there are enough players across the finish line in an instance no other players have to finish the race for personal credit. All that is required is passing through the first gate.
We tested this with only one person from the guild running the whole rush (other instance members ran for the numbers) and it ending on timer; only one person crossing a single checkpoint then ending it via the NPC and having the guild members scattered through the rush but not crossing the line. As long as they have that first checkpoint it counts when the rush is ended.

We had that exact issue to and, on the topic of guild missions, we could not complete one of our bounties because we kept getting either poobadoo or brekkabek both of which are bugged.