At present, a Category will only Onebox if visible to everyone. For example:
https://meta.discourse.org/c/lounge/20
Unlike Topics, it won’t Onebox even if being posted from within that category, so this can’t be easily worked around.
It would be super helpful if internal category links resulted in Oneboxes - especially for building easily updatable (just a rebake) showcase topics that outline the private content available on a site.
Perhaps this could be a setting? Some categories may be only known to certain people, but the description gives it away and they don’t want that?
In cases where the “about” topic of a category oneboxes, the category could onebox too. The information is the same:
But when you do the same within lounge with the link to the lounge category and its “about” topic, the topic oneboxes, but the category link does not.
I know. Basically, what I am suggesting is that it could be the intended bahaviour.
Why do you think it’s intended that one of the two works in private categories?
I think it makes sense if both work alike.