There seems to be a bug in the database time fields...
If I add a record that has time fields in it, then go back and edit the same record and don't change the time fields, they are saved blank/empty. It seems to have something to do with the "am" / "pm" that is added on automatically by the system - if I edit the "am" / "pm" out then it saves fine, but if they are left in the field is saved blank.