When an active sync is underway, if you click Pause and then restart the Creative Cloud desktop app or your computer, the Files panel goes blank and shows a continuously spinning progress wheel.
Try the solutions below to troubleshoot the issue.
Hold down Ctrl key while pressing 'Quit' button under Preferences. This step kills all the CCDA-related processes together such as Adobe Desktop Service, CoreSync, etc.
Uninstall the Creative Cloud Desktop Application using the uninstaller available at https://helpx.adobe.com/creative-cloud/help/uninstall-creative-cloud-desktop-app.html, and then reinstall.
No restart of Windows or MAC is required.