Mirror Blade (GS #2) shows out of range when I am at max GS range (1200). I have confirmed in multiple zones using static enemies, such as dragon crystals for Jormag. It does no damage, does not apply vulnerability, and the clone does not summon. The range on the first 4 GS abilities is set to 1200.
All the other abilities seem to work fine. Mirror Blade works fine at less than max range, although I don’t recall exactly how much less. The difference is definitely enough to notice, though.