What went wrong?
Even after reaching 800 stability, I am not able to skip to doing the LAST quest echo (Lair of Formossus) in the timeline…instead I have to complete the 2 OPTIONAL quest echoes to be able to use the supposedly last echo quest.
Clicking on the ENTER THIS ECHO button only makes a sound.
This is happing to a lot of people. As a work around, you can do the two “optional” quests and then you can fight the boss. That worked for me and other people.