stuck - EoS "defeating the kett" quest

Same issue here, although I did defeat the Invictor and got to the observation room to finish the quest. On my way back however, I got killed and the auto save put me back right after the point the Invictor was killed. The additional items and stuff I got from the observation room were lost. Now no longer a way back through the door that was opened previously after having killed the Invictor.

Strange things have started to happen after having tried for a long time to get that door to open again. I ended up having a 'new' Journal entry showing, but going through the full Journal will not make this disappear. The Kett continue to spawn and fight me in each section of this base, although this may be intentional. Often the Kett are able to shoot right through objects as well, which not only happens here by the way. I got some weird floor or huge black slab to show up which was not there before and should not be there either (see image). Moving away from this base did not allow me to save for a long time, I was still in combat even though far away from everything. Later on, after picking up on new quests and going other places, the map for this base kept showing up, even when I went inside another of these vaults, which was nowhere near the base for 'defeating the Kett'.

Eventually I have been able to save again and besides a stuck 'new' Journal entry all seems back to normal again. I guess I was at least lucky enough to have finished the mission.