Hi @praxisfrankulbrich ,
Thanks for writing in.
I checked and all the content are created in visual composer where shortcode format is too old. It can’t be read by visual composer itself. You should re-compose your content using newer version of visual composer.
This is not theme specific since it’s not working on other themes too, I checked it. Or perhaps, your previous theme has visual elements specific to that theme. Hence, switching to another theme disables that. Example, the
[trx_section] shortcode is not part of visual composer, but your content has it.
Hence, the only solution is redoing your content using standard elements.