Microsoft Office 365 Reporting Add-on for Splunk: Returning "500 Server Error: Internal Server Error for url"

O365 message trace logs suddenly stopped logging. We are seeing following error in Splunkd.log ERROR ExecProcessor - message from "python /opt/splunk/etc/apps/TA-MS_O365_Reporting/bin/ms_o365_message_trace.py" HTTP Request error: 500 Server Error: Internal Server Error for url: https://reports.office365.com/ecp/reportingwebservice/reporting.svc/MessageTrace? We had that verified credentials are valid. Please suggest how to fix this.