Run Inspiration not working full time

Hey, the merit ability insparation on runefencer doesnt work fulltime always, when i use valliance ot vallation it works but when the timer on it is like 0-60 secs left it sometimes happens that my cast time is the same as without insparation so i think there has to be some Kind of bug, ive noticed that Party members that get affected by valliance and vallation get 2 buffs one for the dmg reduce of elemental spells and one for the fast cast itself, the run always only gets the valliation valliance Icon and it usually works works but sometimes it breaks for some reason, sometimes i still have fast cast with 10 sec left on the buff and when it wears it says "vallation and fast cast effect wears off" but sometimes the fast cast effect isnt up anymore it seems? i hope u can check it