MP3 Metadata - Date Released field

I tag all of my MP3 files with release dates.  When tagging my music files I use Tag&Rename software to update the "Date Released" (format 1990-03-15) field.     Rekordbox imports this data perfectly but it always clears the Date Released field from the original music file.  Why is it necessary to cut this data from the field instead of coping it from the field.  None of my original music files have the Date Release fields populated anymore. Is there a fix for this?