Bismarck Extreme - Add buff stays when one is killed mid-cast.

Time: 7/2/2015, 7/1/2015 and more times
Frequency: Every time my party has killed one of the Sunawa(think that's how they're called) during the cast of either the green or blue debuff.
World name: Lich
Character name: Vell R'ius
NPC name: None involved.
Monster name: Bismarck[EX], O'Sunawa, U'Sunawa
Class/Level: Summoner
Party or solo: Party
In-game time: Not sure when
Area and coordinates: Limitless Blue - Extreme version
Steps:
1. Get to the second phase of the Bismarck Extreme fight.
2. Defeat one of the two Sunawa's during the cast of their debuff.
3. Half of party is nearly unable to attack. The debuff will either reflect damage instantly or is delayed with the reflect. But in some cases it doesn't even reflect damage at all. Other half has no debuff at all.

This happened every time to my party and it is high time this gets reported. There is another topic on the debuffs not working properly but this one is not caused by the same thing as described in their topic. What I have described here only happens when we defeat one of the Sunawa's during their cast of the debuff and half of the party still keeping the respective debuff while the other half doesn't even have one. Sadly, I haven't even thought of taking a screenshot of this happening in my runs as we were too busy trying to rush down the other add.

I hope I have provided enough information on this matter and in the right way.

Having done this fight numerous times, have you considered not trying to rush it down so fast to avoid this happening until a fix is made? The way the encounter works, and how the debuffs are timed, you end up hitting the auto-wipe point before a 4th debuff refresh can occur. So, you can either pause your damage output prior to a refresh occurring, or avoid the breakpoints altogether. Something to consider for the time being. No need to be in such a rush to kill them, if you're killing them so fast that one is dying while they're recasting the debuff.

Actually, we have. But there's been some occassions that the random people joining the groups don't know about this and despite being warned to not kill them during that, still doing that. It's not exactly that we kill them in a rush, but sometimes it is just poor timing if a limit break comes into play.