Updraft-Central-Site is broken with new WP-theme

Hello,
for some time now I have been using the [updraft_central]-shortcode on one of my pages.
This worked without problems with the WP-theme Twenty Twenty-Three.
Now I wanted to try a new theme (Kadence) and the page in question no longer works. It is displayed very briefly with moved elements and then remains white. (All other pages of my site working fine with Kadence.)
How can I find out where the error lies?
I have tried other browsers and also cleared the browser cache – no success.
Thank you very much!