I can confirm that calling out the specific driver name (including ANSI vs Unicode) in the connection string is the only way this worked for me. I have installed 32-bit drivers on both dev machine (Windows 7 64 bit with VS 2015 Enterprise, SSDT 14.0.60413.0) and prod SSIS server (Windows 2012R2, SQL Server 2014) and added DSN using the 32-bit ODBC adminstror. Package would fail on the prod server because it couldn't create connection.

One thing to make sure to execute the package using 32-bit runtime on the prod server.