[Can't unlock The Limbo Theorem quest]

Edit:

I found the solution, which is also relevant to the previous two posters:

This is not a bug. Completing the Junction gives you a crafting recipe for the a quest key that starts the Limbo Theorem, it doesn't unlock the quest itself until you've crafted that. While the text in game could be clearer about this, if you did the Junction, you should be able to craft the key.

["Defeat a PROSECUTOR on CERES" Jupiter Junction mission issue]

Yup, same here. At least six Prosecutors killed, not one of them got counted. This has been a bug for so long now that the best fix may simply be to change the fourth requirement for the Ceres > Jupiter Junction to something else for now.