Flashing Lee Sin Q (Resonating Strike) cancels damage.

Hi guys i just would like some clarification on this since I am a lee sin main and this is not something that just started from patch 4.21 but has been around for maybe a month (that I am aware of). Anyways usually what would happen when you flash resonating strike at the last second would kinda of bug for a moment with lee sin and he would just move to your flashed position. Recently what has been happening is when you flash at the very last moment it cancels lee sin Resonating strike damage. Since this is a lock on ability it doesn't make sense to be able to cancel the damage.

Well let me know what you think , I would link a video of it but lolreplay is currently broken, but here is a clip that Scarra analyzed on stream: https://www.youtube.com/watch?v=UCK_UaaeCEQ

Would be awesome to get a rioter's thoughts about this to see if it actually is a bug. Thanks and GLHF IN THE RIFT :P