If the characters are showing up on your Bungie.net profile but not when you log into the game from Steam, then the Steam account you have associated with your Bungie.net profile (and the account you set up with the Migration) are different from the one you're logging into. You can view the name associated with the Steam account you Migrated to and that you have linked to Bungie.net by going to your Bungie.net Settings, then to Accounts & Linking, and then viewing the identity there associated with Steam. In order to use your Migrated data, you must log into that Steam account on your Steam client. Your characters cannot be moved once successfully Migrated, and you successfully Migrated them to whichever Steam account that is when you set up for the Migration. Please note that changing the linked Steam account will not move your characters. If you need to receive further assistance, do not unlink that Steam account from your Bungie.net profile.