I'm not running 2012 yet, but SSMS (at least in previous versions) is 32-bit only, and therefore the import/export wizard will only see 32-bit MySQL drivers, not 64-bit, so that could be the problem...
Also, I assume you're aware that the wizard is running client-side, not server-side, so if you're launching it from your client laptop/desktop, that's where the MySQL drivers are required to be installed?