Sometimes there can be issues backing up the .pst files from Jottacloud, because of the size of these files and the fact that they change so often. This means that the .pst file is often changed before the upload is done, and then Jottacloud will have to start the backup again. If the file then is changed again and again, the upload will have to start anew again and again.
The two recommended ways of backing up the .pst-files are the following:
Use scheduled backup and set the backup to run when the workday is over. Make sure that Outlook is shut down before backup starts up. Scheduled backup can be found under Settings and Schedule in the Jottacloud client.
Make a new folder and copy the .pst-file to the new folder. Then add the new folder to Backup. If you choose this method you would have to copy the .pst-file manually to this folder, from time to time.