"Bookings with me" does not show calender events

I've been experiencing issues with the "Bookings with me" feature over the past few weeks or months. Previously, it functioned correctly, only displaying time slots when I was available. However, it now respects my working hours but fails to indicate whether I'm already booked or not. Even when I schedule an event through the booking page, it gets added to my calendar, but the time slot remains available for further bookings.

In contrast, the public link to my calendar displays all events as expected.

I've tested this issue with a colleague's booking page, and it worked without any problems. Does anyone have any suggestions on how to resolve this issue?

Greetings from Germany,

Thorsten