[Gameplay] Elixir Bug: Can't Buy Elixir of Iron

Occasionally, late game, I am unable to buy an Elixir. It only happens when I have full build. Usually, I'm able to buy it and auto-consume, but sometimes I can click the buy button a bunch of times, and despite the fact that I usually have well over 2,000 gold a that point, it won't let me buy one.

I've only noticed this bug when using Sion, usually when I jungle with him, and try to buy and Elixir of Iron. At first, it was so frequent that I actually thought that you weren't able to buy it if you have smite or a jungle item, but then in a later game it worked out just fine. I haven't tried relogging, because the disadvantage to relogging late game very much outweighs the advantage of Elixir of Iron in most - if not all - situations. At my current level of play, the "Elixir Bug" won't lose me a game, but I figured I'd bring this to Riot's attention. I haven't seen any other threads about this after I searched, and it doesn't seem to be a widespread/known bug.