Make sure that you have all Windows updates that are available.
The one thing that was causing it for me, believe it or not, was that I needed to do a clean installation of the latest Studio graphics driver from the NVIDIA website. After doing that and restarting, all was OK.
Have you tried restarting your computer? The Creative Cloud app isn't very transparent with the exact steps it's taking, so issues with syncing or downloading are often difficult to troubleshoot. Like Peru Bob, I've had similar issues caused by a number of things, including Nvidia drivers, but the easiest step to take is to restart your computer first. You can also open your Task Manager or Activity Monitor (you didn't say if you were on Windows or macOS) to see if Premiere is still hanging in the background, which is my first guess. If you're not familiar or comfortable with terminating processes from those windows, then restarting will close any stuck remnants of programs.