Check your browser settings: Ensure that the sync feature is enabled and configured correctly in your browser on both Windows and Ubuntu. Check that you are using the same browser account on both systems.

Check your internet connection: Make sure that you have a stable internet connection on both systems. Syncing relies on an internet connection to transfer data between devices.

Restart your browser: Try restarting your browser on both systems. Sometimes a simple restart can resolve syncing issues.

Update your browser: Make sure that you are using the latest version of your browser on both Windows and Ubuntu. An outdated version of the browser could cause syncing issues.

Disable extensions: Try disabling any extensions or add-ons that may be interfering with syncing. Certain extensions can cause issues with syncing.

Clear your browser cache and cookies: Clearing your browser cache and cookies on both systems can help resolve issues with syncing.

Check for conflicts with other syncing services: If you are using multiple syncing services, such as a cloud-based file-sharing service, they may conflict with the browser sync feature. Try disabling or pausing other syncing services to see if that resolves the issue.

If none of these steps resolve the issue, you may want to contact the browser's support team for further assistance.