[GAMEPLAY] Moves That Can Be Charged Do Not Charge Properly

I am not certain if this is a bug or a keyboard issue, or something else.

When I play a champion that has a move that can be charged up, such as Vi's Q--Vault Breaker or Vladimir's E--Tides of Blood, the move does not work properly.

With the same amount and consistency of button-press and holding-down applied, the move will sometimes allow me to charge it up all the way and then release the button to cast the spell. However, on other occasions, the spell will not charge--it will cast instantaneously. There does not appear to be any rhyme or reason as to why these spells act this way. They will just randomly allow me to charge or they will cast right away.

Has anyone else had this issue before? If so, what was the resolution?