Cancel option in My Appointments shortcode not working

Hello -
I am working on migrating one of our sites to a new installation and everything seems to be working great except the 'Cancel' option in the My Appointments shortcode is not actually cancelling the appointment.

"Allow client cancel own appointments" is set to Yes
The shortcode I am using is: [app_my_appointments allow_cancel="1" strict="1" title=""]

Not sure why the cancel option is not working. Please help. I need to go live this weekend. I have already enabled Support Access to the site.