Anubias don't like their roots buried. tie the anubias to the driftwood with the roots in the water. The only anubias I have with roots buried is in a 20 gallon tank with reverse flow undergravel filtration, but before doing reverse flow that anubias was just struggling, and now it is thriving.
In my 75 gallon I have an Anubias that started small in a split in my Manzanita root, and now it goes almost across the tank.
I use Flourish Excel for fertilizer.