Guild Wars 2

I took the trait Last Stand (defense 20) which should automatically activate the skill Balanced Stance.
it doesn’t work

Dungeon: Citadel of Flames
Server: Ring of Fire
Mode: explore
Group: 5 players

Tested in all 3 choices

In the final reward are assigned different numbers of tokens, there ’who takes 30, 40 or 60.
unfortunately I will always take the minimum. 30 or 15 like last night.

are 4 times that happens to me, there ’a way to have my missing?

please fix it.