Concentrate Bug

Description of the bug: (optional screenshot/video): Concentrate disappeared prematurely. Notice nav button cooldown icon (pgdn) and missing Concentrate icon in buffs.
What is supposed to happen?: Concentrate should continue with its full duration.
Where did you find and/or notice this bug?: Horntail Cave
A step-by-step guide to re-producing this bug (optional): Not sure
Extra information (optional):

 

I was able to recreate the bug during lag, and I believe it may have something to do with client lag.

 

Character shows concentrate animation and sound byte but no buff is added. Skill goes on cooldown.

 

Bump

 

The skill gets used but the buff does not apply. My guess would be that the system does the following:

1. Cool down check
2. MP check
3. Starts cool down timer
4. Starts skill animation/sound
5. Consumes MP
6. Applies buff

If it gets stuck on Step 5 after getting drained or 1/1'd, perhaps the buff does not apply. The simplest solution would be to move step #3 to the end, but that might have dpm implications on things like Snipe or HH.

There's a couple of other interesting things like this in the game. For example, if a mob hurts you but you had entered a skill to already kill it, your character sprite shows damage being received, but your HP bar doesn't go down.