When terminating an employee, the Leave page will get stuck on a loading icon if the employee does not have an absence period scheme assigned or if the scheme is set up incorrectly.
You can correct this by selecting a different scheme for the employee:
Search for the employee and go to their profile.
Click Absence, then Leave.
Click Change Absence Period Scheme.
Select a different option than the one that's currently assigned and click Save.
Go back to Employment and click Position.
Click Termination to start the termination process again.