The data_engine probe would not stay up and running and the log showed errors indicating that the CM_METRIC_UNIT table was missing.
Aug 21 10:03:11:330  de: [QoSData] ExecuteRecords - 1 errors Aug 21 10:03:11:330  de: (1) ExecuteRecords [Microsoft OLE DB Provider for SQL Server] Invalid object name 'CM_METRIC_UNIT'. ... Aug 21 10:06:11:456  de: COM Error [0x80040e37] IDispatch error #3127 - [Microsoft OLE DB Provider for SQL Server] Invalid object name 'CM_METRIC_UNIT'.
- Suspect either a deletion of tables or restore from backup that did not complete properly due to the number of missing tables in the database schema.
- UIM 8.4 - data_engine v8.4
Reran the UIM installation to repair the schema which was missing many tables, including many CM_* tables then the data)engine started without issue and the error subsided.