I reinstalled DB2 and the multi-select is properly modified when I open and apply the MRT behavior now....sort of.
The page is only partially loading due to an error in the multi-select. I turned on debug in the rsobj.php file and the only option in the multi-select shows "Truncated incorrect INTEGER value: ". I am trying to figure out what is causing that at the moment.
UPDATE: The above issue is no longer an issue. The "Truncated incorrect INTEGER value: " message was caused by not uploading the new version of rsobj.php to the server. I thought I had uploaded it but apparently not.