I'm trying to publish an appointment which has 6 hours duration (configured from 12:00 to 18:00) but when I click on Preview, I get this message: "we are sorry, we are unable to book your appointment. See other appointments or contact us". Basically, I get the generic error which shows up when no more dates/hours are available.

However, I have another appointment of 4 hours duration (from 15:30 to 19:30) and this does work as expected when I click on Preview.

I don't understand why the 6 hours one works and the 4 hours one doesn't. In both the time duration match the hours schedule, as defined above.

I'm using Odoo web app.

I appreciate any help, regards.