Some PTO requests may never be approved or denied. It’s possible that the admin or manager who is supposed to approve the request forgets about it entirely, and never makes a decision on whether the employee can or cannot take the requested time-off.
If a request doesn’t get approved or denied, it gets flagged in the pay-period finalization flow. When finalizing hours for a pay period an admin will have to confirm whether or not the employee took the time off. They cannot continue with the finalization until it is either approved or denied.