I think I've figured out the issue. Somebody on the Discord posted that unplugging their GoXLR sorted the issue and I'm running Voicemeeter and disabling that fixed it for me. BO2 has always had weird audio issues so it makes sense.
From a bit more investigation it seems like I can continue to run Voicemeeter while playing BO2 as long as I'm not running any inputs through it, so it maybe seems like the extra inputs rather than outputs is the issue, so keep that in mind.