Brendan Kiel from Gameservers.com tell us that they "are currently working directly with the game's developer as well as running system checks on our own end to determine the precise cause of this issue. We are nearing a solution and should have a correction in place in the very near future."
For those of you more concerned with the remaining game performance bugs, this is what JD_2020 tells us know Treyarch are currently working on in-house:
- GPU hitching on certain graphics cards.
- Incomplete server browser results.
- Improvements to Quickmatch joins (results with better ping and reduced lag).
- Zombies "The game session is no longer available" error.