Hey Dave,
Welcome back. I attempted to reproduce the behavior on my test environment but was unable to do so. I see you checked ‘Yes’ to reverting back to the default WP theme and deactivating all plugins other than ours, but can you please confirm this? Please review our Testing for conflicts guide and reply back with your findings.
If you’ve done that, it would be best to set ‘wp_debug‘ to ‘TRUE‘ on your wp-config.php file to see if any errors display at the top of the page when you press the Previous/Next Events buttons.
Let me know the results and we’ll go from there. Thanks for reaching out and have a great afternoon. Cheers!