Speed Infusion (SI) for Night Lord

Description of the bug: (optional screenshot/video): SI disappears before timer runs out.
What is supposed to happen?: SI stays until timer runs out.
Where did you find and/or notice this bug?: Presume everywhere, for me particularly HT and Zak.
A step-by-step guide to re-producing this bug (optional): Not entirely sure.
Extra information (optional):

Sometimes when we go bossing with a Buccaneer, and if I am in the same party and get SI, I notice I always lost my booster/SI and attacking at a slow speed. I did not really think about why, but I yesterday while I was doing Zakum, I saw the SI buff just went missing before the timer runs out, i.e. disappear at about 50% time.

I tried a few times and this is just my hypothesis:

a) I use claw booster.
b) Buccaneer use SI, SI will overwrites claw booster. And this first SI will stay until the timer runs out, i.e. till the bar is max, and flashes a few times before disappearing.
c) If Buccaneer use SI again before the previous SI is finished, this is the SI which will go missing. The time when it disappears is random. I think it follows the timer of SI 'b)'. Meaning that when the second SI is used, it does not overwrites the first SI.

So I had to use claw booster to overwrite SI everytime.