NPC's spawing under terrain...

If I left-click to throw -- the grenade throws, explodes, then says that ...whatever type I threw..spawned under the terrain and was destroyed.  if I throw with a right click; it seems to work fine.  

I am running a custom map (from a creater here on codefling), if that makes a difference.   Just wanted to pick your brain and see what may be causing that weirdness.   Thx Zeode!

I have the same issue on occasional throws.  It's much more common if I'm in vanish mode.

After more testing, it is related to roads and the tarmac of Airfield, and not about vanish mode.  I suspect that the ground is slightly lower than the road/tarmac.

I will try and find time to look at this at some point.

Vanish won’t make any difference.