Editing in Visual Composer does not work correctly in Highend Theme

When trying to edit certain pages or posts that have been edited with visual composer before, i run into a loop and the page or blog won’t be openened in Editor anymore. Some pages can’t be edited anymore.
When trying to edit a certain post, a completely other post opens in visual composer.
When trying to add a new page visual composer is no longer accessible.
Cannot use my blog anymore.
Please help.

URL: http://www.fotodesign-winkler.de/blog
Best regards,
Frank