Not sure if bug or working as intended - having put points into the Rogue Initimidation AA, which "causes successful uses of your Intimidate skill to trigger Shadow's Flanking, which increases the damage your target takes from backstab attacks"... Is the Fear part of the Intimidate still intended to trigger? Occasionally get a mob run away, and think it might be the intimidate that's doing it. If so, could the fear part be removed? It's only ever a hindrance than a help.
Are you using Ligament Slice? That has blind and can cause mobs to run away similar to when they are feared.
Its not intimidation or def shouldnt be, never had it run. But as posted before Ligament Slice should be removed from any and all hotkeys until they decide to remove the blind portion of the disc. Till then its to risky to use.