This release addresses a major flaw in the update process of 7.x-2.2 where mailchimp_lists_update_7200() was silently failing and didn't create the 2 additional required columns in the mailchimp_lists table. This release should correct the problem both for those who updated to 7.x-2.2 and those updating directly from prior releases. Just grab the code and run update.php or drush updatedb.