Java moss dying?

I have a question. It looks like my java moss is dying or is dead. This makes little to no sense to me. It's in a 10 g aquarium with dual 6700K LED lights with 660 nm infrared lights. Light is on 10 hrs a day, temp is 81 degrees, ph is 6.7. Plenty of driftwood. I supplement with fertilizer twice a week and use root tabs along with flourite substrate. My other plants - crypts, ferns, helferi, and swords are growing fine. Literally fine. Roots are across the whole bottom of tank. My moss is like completely dead though. Any explanation? Nitrates are at bay, and I use Purigen as my media in my filter from an aquaclear 30. My other two tanks have no issue with keeping it thriving and one is only a 5.5 gallon! The lighting is less sophisticated too!