Face of the mountain bug?

I'm not sure if this has already been addressed or not as when I metnion it in-game everyone has the automatic response of "try re-binding it to a different slot" but yeah. There re random times where I clearly have charges for my face of the mountain (or any of the sub-items that make it that have charges) but it will not use them. I main leo....so at first I assumed it was player error- i adjusted my hit timing. Then I thought maybe it was a visual glitch- that i could see the charges but i really didnt have them available yet...but that seems unlikely with 4 charges swirling around you at once...No -go. It doesnt matter if my adc is full health or about to die. If it bugs out it bugs out- immediately, or repeatedly re-binding to other slots does not fix the problem either. The only thing that fixes it seems to be a random amount of time. Not sure if it's only with leo, shes the only melee champ I play as support....

It doesnt happen often- maybe one out of 10 games or so, but thats often enough to slightly annoy me and make me wonder why it hasnt been addressed yet. Anywho- anyone else have this issue, anyone else seen this issue addressed in threads, and to what end?

Thanks!