1 hour bookings block the rest of the day

If someone books a 1 hour slot on a day, the rest of the day cannot be booked.

The hours show as available but when someone clicks on them it says:
‘There are no services available for the period you selected.’

I was told that the days should not begin at 00:00 and end at 24:00 so I have created a brand new calendar (not a clone/duplicate), I have set the days to end at 23:59.

I have made a 1 hour booking to show the problem – March 5th 2021 on the calendar that I have linked.

I have been trying to get help with this for nearly two months now.

The page I need help with: [log in to see the link]