There's some leftover D7 code that prevents this module from being uninstalled:
Error: Call to undefined function variable_del() in /app/public/modules/contrib/language_header/language_header.install on line 11 #0 [internal function]: language_header_uninstall()
Uninstall the module.
Remove leftover .module and .install files.
Active
2.0
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.