Anyone knows what causes AI fleets to magically teleport through entire systems into 'safe' systems that they literally cannot reach?

In my current game, I had an AI fleet at the planet Zhar, magically teleport through Mon Gazza without interacting with it at all, and then attack Ando. This should be physically impossible since you have to attack a planet you enter orbit of, but they never attacked Mon Gazza, and there is no direct route from Zhar to Ando