Can't approve post in review section

Environment

Discourse Version: 2.7.0.beta3

Plugin Commit: 0cc178d58b

Other Plugins
discourse-calendar
discourse-solved
docker_manager
styleguide

Steps to Reproduce

First step is to have a post to review, I’m not sure how to reproduce this case (in my case it’s because the account is new).
Click on “Approve post” in the review section.

See the message:

You must include at least 1 content_languages tag.

When I click on “Edit” to add the tag, there is no input to set the language

Example

Logs