Eris will contact you through the Crown of Sorrow once she has formulated a new plan, and encourages you to continue to explore the Derelict Leviathan and contain its Nightmares in the meantime.
This quest will progress at the next weekly reset.
It is clear there is more going on than meets the eye. In spite of there being only one more connection remaining between Calus and the lunar Pyramid, he has not struck back against the Vanguard. He is biding his time, waiting for something, and Eris is determined to find out what.