Migration Manager doesn't correctly pick up a separate database server
I think this is probably just a bug. I'm moving from a single tier architecture to a split between application and database. The Migration Manager moved the database to localhost, even though Plesk recognised that the default database server was a separate machine.
Joseph Miller shared this idea
Yes, it looks like bugreport but not feature request. Sorry we cannot confirm the issue, so the request is closed. If you want to continue discussion or get advice from the community, please continue at http://forum.odin.com/
Also I can recommend you submit this report here http://www.odin.com/support/plesk/bugreport/