Hi Nathan, please check if creative cloud is still syncing some of your files or not. Please share the OS version that you are using, so that we can assist you appropriately.
Does it makes any change? Should syncing prevent from sleeping or shutting down? What kind of pseudo-development is that, mister?
If you have multiple programs are open it gives you a prompt to wait or force shutdown the machine. Have your tried to end creative cloud app and then tried to shutdown?
Awaiting your response.