Champions disappearing during back?

I was in a game as Janna and the enemy Alistar was backing. In an attempt to stop his recall, I moved towards him to auto. Alistar didn't move; however, his player model, health bar, AND backing animation all disappeared as I was moving towards him. The backing sound did not stop. At first I thought I was just crazy and maybe Alistar somehow miraculously moved into a near by bush without me noticing. I warded the bush, and he was not there. I could still hear the Alistar recalling next to me in the same spot though. The recall finished and Alistar backed. I asked a fellow teammate if they saw what I had seen, and they verified that Alistar did in fact completely disappear mid-recall. The teammate also said that it was the second time they saw this happen. I'm a little sad I wasn't able to get it on video or a screenshot, but I know that this happened and it wasn't in my head because I had eye-witnesses.

Any answers for what this may be?

EDIT: Somebody downvoted this and yet this has happened to me again with a backing Jinx literally last game lmao