Already if you stand completely behind a wall:
There are spot that are bugged however mostly either with the Sombra crouching or with weird height differences Im still testing for those but till now all I could find are more beneficial to the one getting hacked and pretty bad for Sombra herself.
For the hack not breaking instandly after going further then 15m that is probably intended because if you would stand at exactly 15m hack would likely weirdly bug with the animation of starting and breaking hack tho here too im still testing.
Probably making an educational Post about hack this weekend