Reading through this post http://getmusicbee.com/forum/index.php?topic=18038.0
, shows up a conflict between Episode Date and Release Time.
Episode Date is saved in TDRL (doesn't get saved in TXXX/TDRL if v2.3)
pre-defined custom tag 'Release Time' is also TDRL
you can't use Episode Date as the tag name if you try to match it to Release Time as a custom tag
set up Release Time as a custom tag and info saved as Episode Date in TDRL is ignored by MB and does not show in tag editor, but Episode Date does show in Tag Inspector.