Qlik Sense - Community Sheets or Object not saved once created in the application

After creating Community Sheets and Objects in your Qlik Sense application, they disappear once you refresh your browser or reopen the hub. 

It appears that they are not saved.

When you create a community sheet and/or object, the Qlik Sense Engine will take care of the update in the QVF file and then the Qlik Sense Repository Service will populate the references of those objects in the Qlik Sense Repository Database.
For some reason it can happen that the Qlik Sense Repository Service fail to commit the change. 

If you go in the Repository, System logs (Default: C:\Programdata\Qlik\Sense\Log\Repository\Trace\System.txt) and you might see this type of error: 

ERROR System.Repository.Repository.Core.Repository.Common.TransactionUtility    93    3a32c123-4d20-4c3a-8feb-6b776d24015c Error when committing.    Aktualisieren oder Löschen in Tabelle „BinaryDownloads“ verletzt Fremdschlüssel-Constraint „FK_BinaryDownloadProperties_BinaryDownloads_BinaryDownload_ID“ von Tabelle „BinaryDownloadProperties“↵↓An error occurred while updating the entries. See the inner exception for details.↵↓An error occurred while updating the entries. See the inner exception for details.↵↓Failed to save data into database↵ ...

 

In this case, a restart of the Qlik Sense Repository Database is usually sufficient to resolve the issue.