Issue Summary

Cannot book event if an "availability: free" event conflicts with the desired time slot.

Steps to Reproduce

1. Create an all-day event on a linked calendar, but set your availability for this event as free
2. Go to availability -> troubleshoot
3. See the event listed there
4. Try to book an event on that day
5. Can't ("All booked up")
6. Remove the all-day event
7. availability troubleshooter no longer shows event
8. User is able to book on that day again

Technical details

• The linked calendar in my case is a self-hosted Nextcloud calendar linked as a CalDav integration