All guided rockets/missiles in the game, are directly and only connected to overall visibility in video settings, that overrides or doesn't take into account what overall visibility and objects are set via setViewDistance/setObjectViewDistance in the mission.
100% reproducible even in the editor, just by placing a heavy AT soldier, setting desired setViewDistance/setObjectViewDistance and then just lowering/increasing overall visibility in video settings.
P.S. - objects visibility in video settings and setViewDistance/setObjectViewDistance via console doesn't matter at all, only overall visibility in game video settings matters.