It seems that when Lash and the opponent are not on even ground, the edge of his radius is very inaccurate. I know the ult zone is sort of a zone or sphere, but the detection for the edge of the view cone and the range of the ultimate are wildly different.
I've seen this one a bit often as a Lash main, has to do with his ability to bring down aerial opponents with him when he uses his 1 mid-air. Sometimes the caught opponent seems to get stuck in the geometry and therefore stuck to Lash. It ends after a set period of time, but still super annoying.