there are reports that various things can cause this.
Having the quests “Tol Dagor, The Fourth Key / Tol Dagor, The Ashvane Overseer” in your log.
If you have either of these in your quest log, abandon them.
you can’t access the chamber of the heart until you have obtained your heart of azeroth, which involves completing the introductory quest chain up to “A Dying World”, which starts from the Earthen Guardian.
Nothing you’re experiencing is bug related, you’ve just done things in an awkward order which is confusing the standard process of progression.
Completing quests doesn’t lock you out of completing other vital quests.
Other stuff to try:
Make sure you’ve got map tracking for “Low Level Quests” enabled.
Go directly to Silithus, ensure that you’re in the correct (BFA) phase.
If not, talk to Zidormi (marked on your map) ask her to take you to the current time.
Then fly back to the camp in Silithus, and see if someone there will talk to you.