Game Mechanics: Archery (all ranged attacks?) non-functional near max range

[Ciroco]

Occasionally when you attempt to fire an arrow near whatever your maximum archery range is, the ranged attack hotkey will depress/gray out, but no arrow will fire. This is separate from the "Error: timer not up" message.

I'm not entirely sure what's causing the problem, but it seems that I've been able to replicate it on mobs with large hitboxes (dragons, giants, etc). Since a patch or two ago, it has become impossible to hit dragons at >300 range.