I just installed PRO on a site that had been running TEC for a while.
When I went to /events/, I saw that the “show only first recurring” checkbox was showing up even though the setting checkbox was unchecked in the backend.
After confirming that my memory of the setting was correct, I made a guess that saving the Settings page (without changing anything) would make the checkbox go away. Voila. Problem solved.
I haven’t tried to recreate this problem again, but I believe that the default value or the setting (or how you’re setting it) isn’t working with the check for whether to show the front-end checkbox.