Possibly something that may already be addressed - this is in FME 2019.2.3.1
If reading a date time field from Oracle, if you try to sort this field numerically you get an error message, presumably because the date times are seen as strings
Failed to sort Feature Table. Ensure fields you wish to sort by are of a sortable type
Breaking bulk mode, e.g. with a python caller, addresses the issue and the sorter works.