Hi Till,
We are sorry for your difficulties as you are unable to sync files in the Creative Cloud application. To investigate the issue, could you please let us know what type of file is not syncing in the application, also the Creative Cloud Version installed on your PC?
Do you see any error messages in the Creative Cloud application? Could you please let me know if you tried pausing the sync and then logging off the creative cloud? Then re-logging in and starting the sync again. Also, we have an article link below to refer to, please go through it in case you miss any steps of troubleshooting.
https://helpx.adobe.com/in/creative-cloud/kb/arent-my-files-syncing.html
If the above troubleshooting does not help, I would recommend uninstalling and reinstalling the Creative Cloud desktop application. Please refer to the below article link to perform the steps:
https://helpx.adobe.com/in/creative-cloud/help/uninstall-creative-cloud-desktop-app.html
https://helpx.adobe.com/in/download-install/using/download-creative-cloud-apps.html
Please let me know how it goes and if the troubleshooting provided above helps.
Regards,
Neelam