As recently as patch 5.16 Anivia has a bug where her q projectile disappears immediately after casting and does not reappear. The bug does not seem to affect the debuff application or damage of the spell. However, it is extremely hard to time its reactivation.
Anivia has had this bug since she was introduced to LoL (someone correct me if I'm wrong). And it won't be fixed unless you can find a way to have an 100% reproduction rate of this bug and then report it. No offense, but every time Anivia is in the free week champion rotation there is someone that makes this post. Just use the search button on the boards, reddit, or even the old forums and you'll see what I mean. I'd love for it to be fixed but it just doesn't seem possible until someone finds the cause, and as of yet no one has, so we're out of luck. From personal experience, it seems to occur when the Q projectile travels through minions or when you auto attack just as you launch the Q, but again if it's not 100% reproducible then there's almost no chance of the bug getting fixed.
