Guild Wars 2

Right after you talk to the 2nd team leader, if you do not get into combat, Trahearne will start talking about how he is going to lead everyone out of the cave and to follow him.

For those who can’t get the 2nd team to follow, please try this:
1. Clear out the area of enemies where the 2nd team is located. No need to clear out the whole cave.
2. Walk all the way into the room where 2nd team is gathered. Do this to avoid getting into combat with the grub that will spawn later just outside the cave.
3. Talk to the 2nd Team leader and trigger the next part of the quest.
4. Important: Wait for Trehearne to give his speech. Do not enter combat or aggro the Grub until he finishes talking!
5. The 2nd team should now follow.

I have also encountered this issue. It doesn’t work all the time. I have noticed that most of the time when I don’t get the buff is when there is a lot of people standing the AOE. Maybe there is an issue where if there are too many people standing in the AOE, not all of them will get it, including myself. ArenaNet, can you check on this to see if this is an issue?

After doing this quest 5 times, I finally was able to finish it. With regards to the problem where the 2nd team will not follow, here is what I did:
1. I cleared out the entire cave of enemies. I left the veteran boss at the 2nd team for last. (Not sure if this matters or not).
2. Before talking to the Asura in the 2nd Team, I walked all the way into the room where the 2nd team is huddled.
3. Talk to the Asura and choose the conversation that triggers the next part of the quest.
4. After the conversation, a grub spawned just outside the room. I resisted the urge to kill it. I stayed where I was and did not move. I waited until Trahearne gave his speech about him leading everyone out of the cave (about 10 seconds).
5. I moved out of the room, killed the grub and the 2nd team followed me.

I think the key is to not enter combat right away after talking to the Asura in the 2nd team. If you do, Trahearne doesn’t give his speech and the quest bugs out. No speech = No progress. So it is important to make sure there are no enemies around the 2nd team area and that you do not enter combat until the speech is finished. I hope this solution works for someone else.