This isn't about the level 20 ultimate talent.
There is a brief "arming phase" where Nova locks onto her target before shooting three bullets. When something happens to her target during that phase (allied Devouring Maw, Divine Shield, etc.), sometimes Triple Tap is placed on the full 100 second cooldown, other times it is placed on a much shorter 10 second cooldown.
What triggers this 10 second cooldown?
Is this a timing issue? I believe if she is interrupted after the shots start going out, Triple Tap is always put on the full cooldown. Maybe I'm just seeing the ability get blocked right as the first shot goes out?
Is this ability-specific? Does stunning Nova have a different effect than a Devouring Maw or Void Prison on her target? And is that different from a Divine Shield/Sanctification on the target?
Is this determined by whether the line to the target was interrupted by an ally or an enemy hero? For example, is there a difference between an allied Void Prison and an enemy Void Prison on the target?