HELP! Can't Progress Story after Co-Op

A friend and I recently started playing the game and we have been playing together in co-op for the majority of the time. We finished the main story campaign on TVHM, with my friend hosting the game. Returning to my own game, the story is not finished yet. I already knew that there was this fast forward option, so I didnt think much of it. However, when I want to progress on my story the game seems to be stuck in the In the Shadow of Starlight mission and i have no option to continue. The questlog is giving no instructions. The Siren gang is standing at the control console in the Pyre of Stars map doing nothing. Interacting with them only lets them recite their voice lines. Typhon is already dead in the corner. When moving to the Promethea pedestal, or any of the other pedestals, I can’t place the vault keys. (they are still displayed in Tannis laboratory)

Flying to another planet and then back to Nekrotefayo triggers Tannis’, Liliths and Ava’s initial voice lines, but that’s it.

I already searched online for a solutions, but nothing seems to work. Restarting the game, fast travelling to another map, my friend joining my game and I his, changing characters, all futile. I tried matchmaking but so far the game only matched me for takedowns and trials. I can join takedowns, but I cannot start one on my own since the campaign isn’t finished

Does anybody know a solution so I can finish the game with my own save?