Since the plants are new-it might be emersed-v-submersed growth change over.
On your swords and any rosette plants, I would pull them up a bit and get their crown above the substrate. Pinch off the yellowing/dead leaves. If I understood correctly-you have one of the anubias planted-if so, it needs to be attached to something.
You may have posted this and I missed it...but what is the photoperiod or how long are the lights on.
Root tabs should be crammed as far as they can go into the substrate and fully covered by the substrate.