Hey Marty,
Thanks for reaching out to us!
It looks like this is a bug in the function that will be addressed in our upcoming release. As a temporary fix, find the lib > the-events-calendar.class.php file within the core events calendar plugin and change line 2546 from
$eventUrl = trailingslashit( esc_url_raw( add_query_arg( 'tribe_event_display', 'past', $eventUrl . $this->listSlug ) ) );
to
$eventUrl = esc_url_raw( add_query_arg( 'tribe_event_display', 'past', trailingslashit( $eventUrl . $this->listSlug ) ) );
This should fix the issue that you’re currently noticing. I apologize for the inconvenience of this issue. If you have any further questions, please don’t hesitate to ask.
Thanks!