in the first quest echo for this timeline, Yulia stands at the begining of the echo. She asks that you destroy the 3 soul repositories. After doing so, you have to reach Yulia and you go in another dialog where she states that she cant fight the void no more and the you get the Put Yulia out of her misery objective which is to actually kill her. Fought her once and got OHK by cold attack (which wasnt even visible on screen). Pushed back 3 echoes. Did 4 echoes more to get back to the 2nd quest echo. Entering the echo, Yulia stands at the begining of the echo with the dialog option but once you agree to destroy the 3 soul repositories, no objectives spawns on the map and the actual written objective is Put Yulia out of her misery … Went to the part of the map where the fight ususally takes place and she’s not there. So it is impossible to progress the timeline. Logs included. Thx 
Player.log (23.3 KB)
Player-prev.log (1014.8 KB)
EDIT : TP out of the timeline, redid the choes to get back to the 2nd quest still same bug.
EDIT part 2 : I resetted the monolith and did echoes til the first quest echo. When entering, the dialog option is now ok (Speak with Yulia). She asks to destroy the 3 repositories. Did all this, went to speak to Yulia and for the sake of science 
, I let myself get killed. Redid all echoes to get back and the dialog option upon entering is Put Yulia out of her misery so the bug can be reproduced and no progress can be made. Restting the timeline is the only option I found.