Pending appointments not removed but marked as completed


I'm asking your help because something very strange is happening in my web site: pending appointments should be removed after 5 minutes, as for my settings. What is happening is that they are not removed but marked as completed.

Everything worked correctly up to a few weeks ago. The problem occurs since 2nd sept, when I moved the website to a multisite installation.

To let you troubleshoot the problem directly on my website (as I'm sure this would be very difficult to reproduce) I already granted you support access to the multisite installation.

Please take a look at
Appointment 3685 with client "PROVA ANTONIO" is a test I made a few minutes ago. I tried to book an appointment on the front-end, was redirected to paypal but never completed the appointment. The appointment was correctly shown in "pending" state. After just a bit more than 5 minutes the appointment changed state and is now in "completed" state.

Looking forward to hear from you

Thanks a lot and kind regards