Have you tried dying to reload the checkpoint?
Thanks for the fast reply Raging, so far I have saved as soon as I can and reloaded, I have let Weaver die, and restarted the checkpoint, I have died and restarted the checkpoint.
UPDATE: I deleted every save file even my profile, only left the survival save file, and selected continue instead of load game (this was probably why it wasn't working in the first place) finished the mission and after the credits it popped. Thank you for your help!