Hi Ludwig
I also have the same problem with 4.5 and 2011. I don’t use Page Builder so that’s not the problem. Hopefully someone will have a solution. In the meantime, I’ll keep looking and report back if anything shakes out.
Cheers
Terry
It’s a wordpress bug. I got the same error after just updating wordpress.
Lots of other people as well: for example see: https://ww.wp.xz.cn/support/topic/sidebar-drops-underneath-page-content?replies=11
Here is the ticket that you should follow to get news about the bug: https://core.trac.ww.wp.xz.cn/ticket/36510
Thanks Andreas. I followed that link and updated my functions.php file in my child theme and all is now well. There is also a patch on there but I didn’t know how to use it. It seems that there will have to be a new version of WordPress to sort out the conflict with 2011 and a bunch of other themes.