There's plenty of discussion and even sage advice out there explaining that a caster need not have Line of Sight (LOS) on a target for their Spiritual Weapon to make an attack. I.e. a paladin can summon their SW and leave the room and still be able to make attacks with the weapon.
But is this still the case for maintaining concentration on the spell if you leave the range of the spell?
Another way to phrase the question might be is the range of the spell only a determinate in the initial casting of the spell, or is the range the max "leash" of the spell to keep it active?