When doing OS10 we had 6 people inside and properly had 4 stacks. 1 person DCd while inside while trash clearing and wasn't back so we went ahead and pulled the boss. Since there were only 5 of us left we all properly had 5 stacks. The 6th person logged back in mid fight with sartharion and he was able to join the fight since he was still inside but everyone still had 5 stacks of tenacity even though we now had 6 people and should have been reduced to 4 stacks. My guess is that the stacks probably dont update while in combat or an encounter is in progress.
When doing OS10 we had 6 people inside and properly had 4 stacks. 1 person DCd while inside while trash clearing and wasn't back so we went ahead and pulled the boss. Since there were only 5 of us left we all properly had 5 stacks. The 6th person logged back in mid fight with sartharion and he was able to join the fight since he was still inside but everyone still had 5 stacks of tenacity even though we now had 6 people and should have been reduced to 4 stacks. My guess is that the stacks probably dont update while in combat or an encounter is in progress.