Grouped for a monolith. Friend was the leader choosing echoes.
The UI didn’t show credit for my quest echoes as we did them, but I was able to progress and get rewards for all including the boss.
Further, I had access to the next timeline that we unlocked.
I did not have any stability removed as we did this, though I believe it should have been.
It’s also possible that I gained stability in echoes that I was not in. We had to drop party for a bit while I stepped away, but I was still on the post-Monolith platform with him. It seems I gained stability despite not being partied.
My brother and I had the same issue. I thought we had to complete each quest echo twice. It was the only way it would show the checkmark on the quest Echoes for both of us and remove the stability etc. (We would each open the quest echo and help do each other’s quest). Glad to hear it was only a visual bug and the devs aren’t going to make us repeat each quest echo 2+ times depending on the party size lol.