Lux Ultimate while Stunned [NA]

In the included video you can see Lux clearly stunned and yet her ultimate still goes through. I don't see/remember any where in her kit that her ult will still cast even while stunned. This is the first time I have encountered this bug, but I thought I should bring it to your attention. This occurred during a Solo Queue Ranked game on 9/30/2018. On the NA Server. Thank you for your time and help!