Medium Speed infusion skill disappear after rush skill

Description of the bug: (optional screenshot/video):
I think there is an old bug report which describe the bug but I could not find it so that's why i made this report. Ok, back to the point, so when I used rush sometimes, my skill speed infusion will disappear after. I tried to figured out when exactly this happen but it's very hard to track it, but I'm pretty sure this happens after the rush skill.
What is supposed to happen?: the speed infusion skill shall not be disappear.
Where did you find and/or notice this bug?: When I was bossing or grinding by using both speed infusion and rush skill.
A step-by-step guide to re-producing this bug (optional):
1. get speed infusion skill (also get sharp eyes, because i used to cast this skill together with speed infusion, maybe the sharp eye might affect the bug, I do not know)
2. try grinding or bossing by using the skill by using combo:
2.1 jump-rush-attack&jump
2.2 rush-jump-rush
2.3 rush-jump & attack - rush
2.4 rush-rush-rush
3. if you did triggered the bug, you will see your speed infusion skill is gone from your received buffs list at top right corner
Extra information (optional):

 

Sadly i do not use booster at all during my daily grind.