So after well over a year (may be closer to two) my dendro finally popped out a baby! I believe the key has been increased feeding. I used to feed it 1-3 times a week (some weeks not at all). For the last few months I've been giving it food most days. I feed it hikari mysis (5-15 per feeding), Nutramar Ova (a good squirt from my feeding pipette or spectrum pellets.
I think there may even be another polyp forming on the opposite side!