While attempting to simulate my character, I noticed it wasn’t using Ambush as part of the Subterfuge opener – even when I made a custom rotation to do so. After looking at the Theorycrafting Wiki, it looks like it’s only configured to be castable on Stealth, Blindside, or Sepsis. I can cast it in game using Subterfuge, however, so I believe the spell entry might need to be fixed.
https://www.askmrrobot.com/wow/theory/mechanic/spell/ambush?spec=RogueAssassination&version=live
https://www.askmrrobot.com/wow/theory/mechanic/spell/ambush?spec=RogueOutlaw&version=live