Appointments are displayed on the booking page, although the employees there already have an appoint

Good day,

We have had a booking site through Microsoft Bookings for a few years now. For some time now, we have noticed that Bookings no longer takes into account the times already booked in the calendar of employees.

So if the employee has an appointment in the calendar, the customer can still book an appointment via the booking page.

I have made the following settings in this regard:
1. directly in the settings of the booking page at "General availability" set that "Bookable when employees are free".

2. directly in the settings of the employees is activated that events in the office calendar influence the availability.

3. at the service itself also active that only bookable when employees are free.

At the shown service, I am deposited alone as an employee. For testing, I have created an appointment in my calendar on 03.08. from 8 am to 5 pm, where I am marked as "booked".

Despite the calendar entry, customers can book an appointment on the booking page. The already existing appointment will not be taken into account.

This problem occurs with all employees.

Any idea what this may be due to?
I myself unfortunately do not know any more.

Thanks in advance!