The Impale skill will show as obstructed on a flat terrain with no objects that can obstruct the projectile.
This is by far the weirdest bug I have experienced since it does not happen all the time, only rarely.
Basically the same as your other bug. Nothing specific to this skill. The LOS algorithm is just buggy. It seems to conjure up obstructions where there are none. One shot might hit while the next gets obstructed even though neither you nor the target has moved.
Not affiliated with ArenaNet or NCSOFT. No support is provided.
All assets, page layout, visual style belong to ArenaNet and are used solely to replicate the original design and preserve the original look and feel.
Contact /u/e-scrape-artist on reddit if you encounter a bug.