I have a client with a Windows machine that has been running a database for about a year on FMS11. Part of that database is a backend to an online store that runs off MySQL. I made an ODBC connection and everything was working fine.
When I upgraded to FMS12, it no longer recognized the ODBC connection. It is listed in "Manage External Data Sources", but if you try to edit it and click "Specify" for the DSN, it takes you to a blank list.
I reinstalled the ODBC driver to no avail. The only thing that worked was installing the 64-bit drivers as opposed to the 32-bit. Now it 'sees' the database and can connect, but it crashes when I try to pull up the external tables.