I had the same issue with my ninja pro V2 reg fill nipple.
Bring it to local shop, they also can't figure out. So I just get another fill nipple of eBay (I think techT) for 8 bucks free shipping.
But if you want contact Ninja.. I m sure they will help.
GSL Prestige 2 214, Dye Dam Olive Green, 2013 bob long ripper splash, Empire axe PDD, Planet Eclipse Ego 11, 2012 proto reflex rail Dyecam, DP FX, fully upped ion, tippmann tipx, A-5 and carver one