Here's another issue that we've discovered:
You can get into situations where you want to fire a ranged attack at an enemy. Mousing over that enemy shows it to be a valid target, but terrain is in the way, and the terrain stops the shot. This is inconsistent with other cases. For example, when a monster is behind another monster, targeting the rear monster is impossible because the monster in front is in the way. If you mouse over the rear monster it will tell you the target is invalid and forbid the shot. This gives you an expectation that when the target is valid you have the given chance to hit, but terrain that's in the way blocks the shot without forbidding it.
