The rollover and the Civilopedia (under Unit Abilities: Ranged) say "+1 additional attack per turn if the unit has not moved." But I move them and fire twice all the time. Better Civilopedia has another entry for "expert marksman" which says "+1 additional attack per turn if unit has not used all its movement." Well, the first attack uses all its movement, but I can still attack again. Why not just say "+1 additional attack per turn"? If that's not what you want, then you need to change how it works. Note, this bug was listed as the last post in "Fall Update 2017 BUGS" on Oct 29 2017 and it's still a bug. Or incorrect documentation.