OK, one last time. Let’s say that, until I found the solution that worked for me, many of the steps were just a placebo effect. Steps 4, 5 and 6 don’t actually do anything. From now on, simply exiting via the main menu is enough; there’s no need to change any settings or use any commands. Even so, make sure you check the Plutonium console—not BO2—to see that it says ‘writing stats’.
Also, to ensure your local save is used by the cloud save, you can open BO2 in local save mode with use_localStats 1 and type use_localStats 0 to start saving to the cloud again whilst your local stats are loaded. Play a couple of matches and exit, but not before typing forceuploadstats. now exit via the menu and restart; if you’re still at the same level, go back to use_localStats 1, otherwise go back to use_localStats 1 and repeat the process again. This will create checkpoints in your cloud save with your local files in case an update ever interferes with your progress files.