MailChimp Plugin: "Illegal string offset" error messages

The MailChimp plugin was in the list of plugins to select from, so I chose WPMU Dev Dashboard just so I could submit this ticket.

On the Mailchimp Sync plugin setting page, under the "Log" tab, it shows some history and then lots of these messages repeatedly:

Warning: Illegal string offset 'date' in /home/crownque/public_html/crownrocklp.com/wp-content/plugins/mailchimp-sync/admin/class-admin-page.php on line 713

Warning: Illegal string offset 'message' in /home/crownque/public_html/crownrocklp.com/wp-content/plugins/mailchimp-sync/admin/class-admin-page.php on line 713

I've already enabled support access for the site.