Until CDPR fixes it, there's not really any point in finishing the main mission other than to get the Achievement, since you lose anything you've done in that last part no matter what option(s) you have for the ending. Epic fail for "... an open-world, action-adventure story set in Night City, a megalopolis obsessed with power, glamour and body modification. ... You can customize your character's cyberware, skillset and playstyle, and explore a vast city where the choices you make shape the story and the world around you."