Appointments shortcode broken - won't allow booking!

Hi,

We need urgent assistance with our Appointments+ (used in conjunction with MarketPress) please.

See the attached screenshot. The [app_confirmation button_text="Click here to confirm"] shortcode is not working and the website is just displaying this code on the front end. If you click an available slot, nothing happens.

Please can you help us asap?

Thank you.
Phil.