User Answers not Saving

Using this great plugin on a relatively new site and I’m having a problem. When new users (i.e. not logged into WP) complete a quiz, results are not showing in the CHAINED_USER_ANSWERS database. Interestingly, the correct total points are written to the CHAINED_COMPLETED database.
Everything works normally when logged into WP.
Additional info… I recently migrated the site from one host to another, which may have coincided with this issue appearing but I can’t be certain.

The page I need help with: [log in to see the link]