I had the same issue with 9.23. What I found was the smart group one below the parent config would go by alphabetical order. So my setup was this:
-Laptop Base Config
--Student
---Faculty
The student smart group wouldn't inherit anything from the Parent Config but the Faculty, because F is before S, would inherit everything. I played around with it even more and found if I switched the Faculty and Student smart groups then both would inherit everything. I tried adding a second smart group called MusicStudent on the same level as the Student smart group, which looked like this:
-Laptop Base Config
--Student
---Faculty
--MusicStudent
When I did this again only the Faculty received inherited settings from the parent, both the MusicStudent and the Student smart groups received nothing. I changed my config so it would go by alphabetical order for nesting and it ended up looking like this:
-Laptops
--Faculty
---MusicStudent
----Student
When I nested my groups like this it worked. All smart groups were able to inherit everything but that was a problem for me because I had software that we loaded at imaging time that would only be on Faculty machines and not students so this wouldn't work for me. Since I couldn't have a two smart groups on the same level, I just waited until Casper fixed it. I've since upgraded to 9.3 and they have fixed this issue in that version. I've been able to use Casper imaging like I was in version 8 only with the nested smart groups which make it a lot easier.
