The format of date/time in exported Excel reports are not consistent. Sometimes it is a date string, other times it is a numeric date. This makes it very difficult to sort/filter by the column values.
Set the regional settings on the system to match the format of the exported CSV/XLS. For example :
1. Navigate to Control Panel
2. Region and Languages
3. Update the format to English (United States)
TPAM date format can be set in /admin | System Status/Settings | System Date Format.