Customizer: Can’t change Meta — Bug?

Dear users,

for some reason my customizations in the Meta-section of the customizer (which meta information to display above and below the article and for its entry on the front page) do not work.

When I change an option it doesn’t seem to recognize it: I can’t save it or press ‘publish’, the Publish-button is still inactive even after changing anything in the menu. When I return to the customizer’s main menu to change something else, say custom css, the publish-button becomes active. But even then it doesn’t save any of the changes in ‘meta’.

I could solve this manually with a child theme probably, but since it seems to be bug, I thought I’d share it with you and hear your thoughts and maybe get the attention of the developers.

The page I need help with: [log in to see the link]