If there is any doubt that a file isn't being backed up, please first ensure that file is selected for backup in Settings. (Selection > Custom Selection)
Just Cloud will backup your files once per day with the default schedule settings. If you have added a new file or amended an existing file within your backup selection it will be backed up when your application is scheduled to run.
You can, however, back up a file immediately by dragging that file onto the application or clicking backup now.
If you are sure your files are selected for backup and are not being uploaded during a backup please consider the following: