[Gameplay] Sejuani's W becomes unusable

While playing Sejuani (using the Poro Rider skin) in a ranked 5s game today 10/10/2016, I died while being heavily cc'd. After reviving my W (Flail of the Northern Winds) was unusable. If the skill were activated then the icon would grey out, but nothing would happen. No additional damage would be dealt, nor effects be applied other than from her normal auto attacks.

This is the video (29 minutes in) that shows the last moment where my W works. At the very end of the clip I am unable to tell whether or not my final W was successful, because I died immediately after activating. http://plays.tv/video/57fc3d31a00e29512c/this-is-when-the-bug-began?from=user

This is a video (31 minutes in) showing the bug, and the results of my pressing W within a minion wave. It clearly shows that after activating the skill, nothing occurs, aside from the ability's sound. http://plays.tv/video/57fc3ce1ef40d8d264/sej-w-bug-?from=user

So far I have been unable to replicate this bug. However, if this bug is easily replicated then it completely guts the champion's damage and kit while it is in effect.