2.1.1 breaks event page – 404 error blank page

After the upgrade to 2.1.1 the events display page no longer works, returning a blank page with a 404 error. had to roll back to 2.0.1 to fix. Displays of calendar widget and shortcode is fine, but individual event pages all break. Appears to be linked to the /ai1ec_events/ to /events/ menu structure change. Resetting permalinks or clearing cache made no difference, although did fix this same error for some others.

https://www.ads-software.com/plugins/all-in-one-event-calendar/