Second Employee does not seem to be recognised

I set up a swimming pool booking website with a "Pool Bookings" service and a "Swimming Pool" Employee.

Working Time is set up from 6am to 8pm every day with hourly sessions available e.g. 6am to 7am, 7am to 8am etc.

The Swimming Pool Employee has "breaks" from 8am to 3pm from Monday to Friday because the pool is owned by the school and the school has exclusive use of the pool from 8am to 3pm.

To enable all the sessions from 6am to 8pm for school holidays, I created a second employee, "Swimming Pool School Holidays" which has no "breaks" but has all the school holiday dates enabled in the Components -> OS Services Booking -> Manage Employees -> Swimming Pool School Holidays -> Availability calendar.

Unfortunately, this does not enable all the sessions on school holidays as expected. When I look at availability for the school holiday on October 20th (for example), It should show all sessions from 6am to 8pm but the sessions from 8am to 3pm are still being excluded:



In Booking Configuration I have set:

• Disable timeslot of service when one of employees is booked = No
• Employee can work in multiple services in the same time = Yes

Is there something I am missing?