The new Monolith unlock feature from 1.2 update is bugged. I had character that had done half the unempowered Timelines to completion before the 1.2, then finished the other half after 1.2. I made a new 1.2 character during this process and saw the map unlock the Mono’s for the 2nd character as I progressed. The only ones that did not unlock was 2 and 3 as they were not connected to the Mono’s char 1 completed.
After I finished the first Mono on char 2 I should have had all paths connected, but when I opened my map I noticed the Mono progression had reverted fully so I only have access to the first 3 timelines. I created 3rd character after I noticed this and it shows on the map I only have access to the first 3 Mono’s.