Pretty self-explanatory, the feat sometimes decides not to work. When I say spring attack, it is really in the sense of getting in and out of combat without triggering attacks of opportunity. At first, I thought it was only a specific monster in a specific quest, but now it can be at any moment, with anything. Below are several instances of it, it occurs 2-3 times per fight when it happens (once or twice per week)
Thanks for looking on the matter.
Thanks for looking on the matter.