Muramana Bug on Ezreal

Hello guys!

My ID is DaddyDontGankUs. I recently have issue on using murmana in the game. The problem is everytime I play ez, i cannot use the active of this champion although i have already got the 750 stacks. I usually put this item on "2", which is the most comfortable place for me to press the keyboard. However, I can use any item that has an active with all kinds of champions in the game. I believe i started to have this problem on patch 6.4. And I was hoping it could have been solved by updating to 6.5 patch. But it did not work, at this point. Not only just on "2" but 1 through 6. I want to know if there are any similiar issues happened before and more importantly, how do I solve this. I think there is something wrong with muramana iteself or the champion himself.(I can also use any active item on ezreal except muramana) EZ is one of my main, I cannot play him without muraman in current patches.

Riot, please help me with this stuff. I appreciated.

DaddyDontGankUs