[GAMEPLAY] Attack frame calculations and Flashing Away

So I was playing a volibear jungle game, no big deal. Everything is going smoothly, and I'm pretty built when the enemy team decides to invade my jungle. Fortunate, I was not alone in the jungle and suddenly we were in the midst of a team fight. I didn't survive, but I did manage to get a kill; however, this is where the bug comes in. I forget who exactly I killed on the enemy team, but they flashed away before my attack actually landed. I had no active ult at this time, and even if I did there would've been nothing to chain to. So I'm basically saying: I landed an attack on someone who had already flashed too far away for me to actually land the attack, thus earning me the kill.