AEM 6.3 Content Fragment not showing up in model.json
I have a page with a single content fragment on it, the content fragment works fine and is displayed on the page, both in the author and publish instances. However, when i try to view the page by adding .model.json on it i do not get any contents about the Content Fragment.
The page displays the CF:

The JSON that is displayed is this:

I've noticed that this seems to work on AEM 6.4 but it does not seen to work on 6.3.