The most common reason why the Holiday time off type isn’t available for booking is that Time Off Type for Holidays option has been set to use the Holiday time off type.
This option only needs to be set if you want the system to automatically generate Holiday bookings on holidays. If you don’t want auto-population of holidays to occur, you can disable this setting so holiday bookings can be created manually.
To remove this setting:
If auto-population is in effect, the Holiday time off type is not available for manual booking, to prevent employees from accidentally booking holidays off; when auto-population is in effect, making manual bookings might result in duplicate bookings.
If your organization wants to auto-populate holidays, but would like the Holiday time off type to be available for manual booking, consider creating a separate time off type for making manual bookings. For example, you could create a type called Holiday Booking to assign to employees.