AFK Timer Bug

So I afked, I know it's a bad thing to do but I had to go to the washroom. Anyways, I got the AFK timer I waited for 3 games and then I was waiting till the timer finished for my 4th game with it and then when it finished, it just reset back 20. Has this happened to anyone before? It's the second time it's done this. Riot could you please fix this.

Here is a screenshot. https://imgur.com/a/q9DJv