This day the employee doesn't work

When the cells of the days on your calendars are all empty, it means you missed to configure something from the back-end.

If the first dropdown above the calendars is empty, you forgot to assign your service to your employees (at least one).

Otherwise, if the first dropdown contains at least an employee or it is hidden, you forgot to setup the working days of the selected employee.

The available days in the calendars are generated following the working days table of the selected employee, otherwise all the days will result as closed.