Here's how to resolve these issues:

1. Update Your Booking Calendar to version 10.1.3 or newer
   Ensure you have updated your Booking Calendar to version 10.1.3 or newer. This update addresses cache plugin issues.
   Important! After updating, clear all minimized CSS and JavaScript files and cached pages or posts.

   If you have a paid version, you can request the latest update on this page.

2. For Booking Calendar Versions 10.1.2 or Older

   This issue arises when the Concatenate JS feature in Jetpack Boost is enabled. To resolve this, you'll need to exclude specific JavaScript files from being concatenated in the Jetpack Boost settings.

   Here are the JavaScript handles you need to exclude:

   wpbc-global-vars, wpbc-popper, wpbc-tipcy, wpbc-datepick, wpbc_all, wpbc-main-client, wpbc_capacity, wpbc-times, wpbc-time-selector, wpbc-timeline-flex

   Copy

   To do this, simply copy this list and paste it into the "Exclude JS Strings" field within the Concatenate JS module. You can access this module by navigating to Jetpack -> Boost in your WordPress dashboard.

   By excluding these scripts from concatenation, you can ensure that the Booking Calendar functions correctly on your site while still benefiting from other features of Jetpack Boost.

   For additional info please contact the support of your cache plugin for instructions on how to add exceptions to the pages with booking forms to avoid caching these pages and prevent concatenation of JavaScript files by the Booking Calendar.
   Also check more here.