Started as a minor annoyance, but it is becoming worse now that overall efficiency increased.
Sometimes groups aren’t able to perfectly coordinate the kills of all 6 bosses leaving one boss on small amount of HP after the rest are killed.
The problem is that some pugs join the last fight and, with enough people joining, a bug appears where the boss HP is reset to full.
This bug is not yet as pronounced as it could be, but with more and more people “figuring out” the fight and splitting in small groups (this bug doesn’t appear when zerging) it could become a real hindrance since there are always some people who will swarm the last boss.