“Our event sold out but then some people cancelled. The waitlist has been working, but nobody claimed extra spots, and the event still says filled (has a Join Waitlist button). If nobody claims from the waitlist is it possible to show more spots available?”
The reason why it still shows that the event is full is because the waitlist is still working through all of the waitlisted players, and doesn’t want to allow non-waitlisted players to join.
If you would like for spots to re-open so that the the event has a “Join” button instead of a “Join Waitlist” button, you must cancel the waitlist. When you cancel the waitlist, all the available spots become first come first served for waitlisted players.