Noblets told me how to fix the discussions. This is how to do it (to Masson Thief):
- Go to "Manage the Wiki's Namespaces".
- Click all on: User, MediaWiki, Template, Category, and <Main> (it's highly recommended).
- Go to Talk namespace.
- Click on "What should this namespaces' content model be?" that has a Wikitext as default and replace it with Flow.
- Don't forget to enable VisualEditor namespace.
- After that, just delete the talk pages with the Wikipedia-like talk pages.