Data shuttle - refresh schedule failing


I currently have a data shuttle setup which is on schedule to refresh every 3 hours. The source file is located in SharePoint which gets updated every hour . The name of the SharePoint file is the same and it never changes.My data shuttle keeps failing unless i manually go in and select the SharePoint file and trigger the data shuttle. This isn't the case with my other data shuttles which have been running successfully without any issues. I have tried creating the reports from scratch as well and nothing has worked.If anyone has come across such an issue or know how to fix it, please advice!Thanks!