When creating any smart group (or assignment group, if you prefer), I am very used to seeing my entire list of organization groups so I can easily check off the one(s) as applicable.
Thus, I was pleasantly surprised when I noticed only the top OG along with an ADD button when creating another smart group in one of my environments.
After consulting with VMware support who in turn reached out to the product team, it turns out this is by design ‘if’ you have more than ten (10) child OGs in any of your OG regardless where they are located in your organizational structure.
When you click inside the box above the ADD button, your list of OGs will appear. You can then select whichever one to add to your smart group. Unfortunately, you can only select one (1) OG at a time which can make the task extra tedious. VMware support has submitted a feature request to allow selecting more than one OG in a future release.
If this design flaw can be fixed then this might still be acceptable. Otherwise, one may consider shortening the list of OGs to less than 10 to avoid running into this issue.