I found it. It was a problem with the checkIf function, which was caused by an error when parsing arguments in Handlebars. This error occurred when the SocialSharing plugin was not installed, so I did not see the error at first. Updating Handlebars to the latest version didn’t help either, so I applied another workaround that now works correctly.
Just update the theme to version 2.8.2.0, it should help.