Bookings with me buffer issue

Hi there,

I'm using the 'Bookings with me' feature in O365 to set up 20-minute appointments without any buffer time. However, when I try to create these appointments, it automatically adds a 5-minute buffer before the meeting, even though I've set the buffer time to 0 minutes.

For example, I’ve specified that I want to be available between 17:15 and 18:15, so my expected start times should be 17:15, 17:35, and 17:55. Instead, the booking options show 17:20 and 17:40. Oddly enough, when I set the interval to 15-minute increments, it works as expected, showing 17:15, 17:30, 17:45, and 18:15.

I’m struggling to figure out why the 20-minute intervals are not working properly. Any help would be greatly appreciated!

Here’s a link to some screenshots of my edit screen and booking page: Screenshot link.

Thanks in advance!

Kath