Spells bug

So for the past few days I have been playing and getting to that point where I realized its NOT ME!! I haven't had this issue before so I think its a bug.. I will be playing, and I will be at that point where the enemy zed is right in front of me (literally on top of me) getting ready to ult.. then I press "F" and ignite him because hes low in health and I can finish him off before he can finish me off with a combo of his own.. then after my combo I flash away and wait for him to either ult me or die from my ignite.. he does not ult me, and he does not die.. MY IGNITE DIDNT GO OFF!?!?!?!?

I have had this problem so often that the game I played last literally just now.. I had to smash my face on my "F" key like im trying to break something.. its not the keyboard because its brand new and I can type with it no problem.. see "FfFfFfFf" Feathers Flowers Food foof feed fajsdlkjf.... I can use the key and there is no probem with it unless I bring ignite into my ranked game.. 5 times I died and missed a kill because IGNITE DIDNT GO OFF im super mad that this has cost me valuable games.. the loss of early game due to ignite not going off is real.. im not normally one to complain.. but when I ignite 5 different people for kills.. and I get 0 kills from my ignite.. there is a problem..

yes if you're wondering I did get it to go off 1 time.. I had to press it like 6 times and die because I didn't get a combo off trying to just get ignite off.. I hop e this can be fixed ASAP because ignite is one of the main things I use when playing top or mid.... sometimes support....