Online Agenda does not work anymore

Good day,

We have been using this wp booking system with great joy the past few years. Since a few weeks however it does not function:

– Online, people can no longer select the first and last date for a booking
– the bookings already made do not always appear online (some do and some don’t, and which appear also differs per time).

This is one of the pages as an example (agenda at bottom of page): https://www.happysailing.nl/huur-zeiljacht-dehler-37cws/

How can we solve this?

Thank you!

Best,

Simon from Happy Sailing