No citadel signs in the fog

Hello, 2 days ago I cleared the last visible citadel on my map.
After that, I see no more lights/signs in the fog that can navigate me to the next citadels.

I even killed the boss in Monolith, hoping they would reappear. But no, no new signs in the fog for me.

Is it ok? Did I clear all citadels on the map and the only way to open the Monolith is to buy the keys from other players?

Thank you in advance for your prompt feedback!

Brgs,
Deniss