Hi Bart,
Sorry to hear you’re having problems using the Post and Page Builder after upgrading to WordPress 5.6. What web browser are you using to update your website? While we were updating our plugins to be compatible with WordPress 5.6, we noticed the problems you’re describing can happen intermittently in Firefox. Our developers are still working on complete Firefox compatibility, and in the meantime we recommend using Chrome.
Please let us know how else we can help!
Thanks,
Nicole