Janna's Tailwind buff glitch

First off, sorry the video is sideways. Grabbed my phone quick when I noticed the glitch and youtube won't allow me to rotate it, fssr. As you can see in the video, when I move around as Amumu, Janna's tailwind buff disappears. When I get back to being stationary, it reappears. That has to be a glitch, considering that tailwind increases movement speed 8% but as soon as you move you lose it. I submitted a report already, and I was told to post it here on this forum also, so here it is! GL Summoners!