Sion's ultimate's impact triggers when it shouldn't(imo) [gameplay]

When I use Sion's ultimate with an enemy directly behind me, it just immediately impacts them and ends the ultimate, this may be it working as intended, but it just doesn't make sense for Sion to "impact" an enemy behind himself when he's charging away from them, and it makes it impossible to disengage with his ultimate when an enemy is too close to you. Them being in front of you to stop you is one thing, but when they're behind you it shouldn't stop you. This also occurs when Warwick uses his ult on you when you're charging, as he warps to your position and triggers the impact, maybe this is fine, as he's almost in front of you, but it still seems a bit strange to have it so your Unstoppable Onslaught is so stoppable. This may occur with other champs that warp to your position as well, like Lee Sin, but I haven't had the opportunity to see that yet. To recreate the "bug" I'm sure all you need to do is have an enemy stand behind Sion.

If this isn't technically a bug, I still think it needs to be changed, maybe reduce the area that triggers the impact so that it won't trigger off of enemies behind him.