A possible reason for this could be that some characters in the table name has changed from upper or lower case to a different case. This is picked up and stored in the Datasource_columns table, but not in the Datasource_Tables table. The solution is to delete the table in import source metadata, then save, and then re-import the table. Remember that doing this will remove all column names as well. Export the metadata to an excel spreadsheet before deleting the table and use the excel spreadsheet to populate the column names after re-importing the table.
If this solution is not viable, it is possible to correct the name directly in the Datasource_Tables table. NOTE: it is not recommended to edit the Xpert BI management database directly as this will void the standard support agreement. Contact firstname.lastname@example.org to get help.