Event Calendar WD & Booking Calendar Business Small

Hello,
we have the following problem:
On one of our WordPress websites, a customer, we have two calendar plugins installed: Booking Calendar (Business Small Version) and Event Calendar WD. Both calendars are critical for the website.
The problem arises whenever we enable the Event Calendar plugin.
Suddenly, the booking overview for the Booking Calendar in the backend is shifted right. Meaning it will show the 30th and 31st of the last month and not show the 29th, 30th, and 31s.
We strongly suspect an unintended interaction between the two plugins.
It would be highly appreciated if you could assist us in solving this.
We have also asked the other party for assistance.
Best regards