Literally one day it started working. I don't really know why or how I made it work. I'm sorry I couldn't be of more help but maybe this will be picked up again by an admin or member of staff. I tried my best to document everything I tried.
EDIT: If you're on Windows, maybe try adding all Plutonium/BO2 folders (namely %localappdata%/Plutonium) as exclusions in Windows Defender.