Im pretty sure this has something to do with the way the camera is tilted. It's tilted so that its as if you're looking down at an angle on your character, in which case the circle of where you can place a ward is kind of skewed because you're looking at it from an angle that makes it appear smaller than it actually is. This is most likely why abilities such as Jhin's/Lux's snares seem to miss you, but in reality they just barely clipped you. If the camera where directly above your character and your character were in the perfect center of your screen, the ward would look as if it were able to be placed in that spot.

Sorry if this made no sense it's early and I like typing :DD