Summon reaper of eviscerating

I recently found a bug with the Summon reaper of eviscerating! While building my summon reaper build I wanted to stack cast speed to make my reaper attack faster of course but there is an issue! once I reach .42 cast speed the animation for the reaper full bugs! the animation doesn't perform full and all damage is negated! I have a video I will be posting with this for a better explanation!

Video is as unlisted only viewable here!
https://youtu.be/rIDcNihJ-9Y

Has been this issue addressed? With anought cast speed you just animation lock your minion whom does not preform any attacks...

Stacking cast speed should be a valid play style to this minion..