Patch 6.4 Graves True grit fall off

when playing as graves, your auto attacks are suppose to refresh your timer on true grit to keep it up and the current amount of stacks it has. as is right now, graves will not have the timer refreshed at all after killing an enemy champion and true grit will fall off completely after the timer runs out.

steps to reproduce:

1. play graves
2. use e to get true grit buff
3. while you have the true grit buff kill an enemy champion (after this the buff should start ticking down regardless of what you do, using e again will start a new buff stack but attacks will still not trigger the refresh and the buff will fall off)
4. try and auto attack after to retain e buff (it should not work)

this happens rather consistently, probably 90 - 100% of the time.