How to give an existing server login access to an attached/migrated database
Finally worked after changing the database owner.  The database was reattached by a different user so the owner was something else.

use [database name];
exec sp_changedbowner @loginame = 'loginX';


After that the user loginX was able to access the database.  It still does not show under Security -> Users but the database is mapped for the loginX login on the server.