Getting bookings during blocked time

Question:
I’ve marked certain times as blocked for bookings, but they still appear as available to book.

Product:
Wix Studio | Bookings Calendar

What are you trying to achieve:
Hi, I run a physiotherapy business and use Wix Bookings Calendar on my website for online bookings. Recently, I’ve noticed a problem. Even after I block off certain times on the calendar, it still shows those times as available for bookings.

For example, my business hours for bookings are from 8 am to 8 pm. I blocked off 7 pm to 8 pm (1hour) , but clients can still book appointments of 90 minutes starting at 6 pm, which is causing scheduling conflicts between time of availability and block time. Also adding to it is there anyway that I can add buffer time to the blocked time as well?
Can you help me fix this issue?

What have you already tried:
Researched for similar problem in the forum but no luck.