Columns won’t collapse in mobile view

I am using SiteOrigin Pagebuilder with Thinkup Themes Minamaze Pro theme. I had to update the theme and use the new version of the pagebuilder.
I have a two colums design that won’t collapse correct in mobile view. The right columns won’t move underneath the first columns.
Here is the development site that doesn’t work properly: https://sabikidev.diexperten.ch/£
And here’s the old site – that has to be replaced – that works like it should: https://sabiki.ch/

I’ve tried all the setting in the Page Builder but nothing helped.