Diana/Devourer Bug?

So Just a bit ago I was seeing how Diana did with Devourer, see if it did well. I noticed something whenever I used a Health Potion, every time I did I would loss the Attack speed from Devourer, as if i didn't have the item. I bought more Potions just to try it and every time I used them it happened again.

Edit: It seems to do this on all champions and tried several other items. Only Health Potions seem to trigger it.