Appointment+ Question

This is a link to the page: (Link given in chat). Notice that April is grayed out. And in the settings the working hours are normal.

Each Service has a single service provider. And the Service Provider working hours are normal. There are no appointments and only two appointments are pending.

Yet the calendar is grayed out. Each Service provider is unique to the service. 5 Services, 5 Service Providers.

All Service Providers have normal working hours. Can you please tell me why those fields are grayed out?