Confused: Where do some of these model categories go? What ticket types are they associated with?

I’m going through and creating my own model categories for custom issues.

As I’ve learned, in order for the model category to appear in the new ticket wizard (a.k.a. the ticket types/“big buttons” screen), it has to be associated with a global parent category created by Incident IQ (like “computers,” etc.).

But here’s the thing: there are some global categories — created by Incident IQ — that don’t appear to populate in the new ticket wizard.

Unless I’m wrong (I usually am), these don’t seem to do, well, anything. Like here’s one:

Am I just not seeing where “Onboarding” fits under the ticket types (“the big buttons”)?

I mean, I’d like to use Onboarding as a category, but which of these would the models/issues fall under?

Soooooo I tried to assign models to it, and then I get this error:

It’s a child category? That’s weird because it’s a global category created by Incident IQ.

So then for fun, I head on over to the Model Categories section, and pull up the Onboarding global category provided by Incident IQ:

What’s the point of having this category then? Am I missing something?

BONUS QUESTION: Can we get a list of all the Incident IQ-created global categories and which ticket type they correspond with? I feel like I’m just doing a lot of trial and error to figure out where these point to.

Thanks.