Ahh..Thanks, Daren. I think I understand what Richard is seeing now.
...and in that case, based on experience, if you don't have a defined Control-VLAN (or if the APs cannot establish their MiNT level-1 links between each other for whatever reason), then what you'll see in each RF-Domain is just 1 AP. (Reason for this below)
If the APs that exist within an RF-Domain can't 'see' each other on the network, then every AP in that RF-Domain thinks that they are the ONLY 1 AP in the RF-Domain, right?...and as such, they elect themselves as the RF-Domain manager...because they think they're the only one there!
This ends up leading to the issue you're seeing in the UI. If memory serves, you will also likely see that the 1 AP that shows up in the RF-Domain will change periodically (to a different AP).
Bottom line, as Daren said, confirm you have the control-vlan setup properly. After that, confirm that all of the AP within the RF-Domain can see each other via MiNT level-1 links.
On the controller, issue command on the CLI:
#
show mint links on
The output will list all of the level-1 MiNT links the AP has established (should be one for each AP at the site). If all you see just a single level-1 MiNT link and it's labeled as "self", then that AP is not able to see the other APs in the RF-Domain. If that happens, confirm that the VLAN is not blocking MiNT traffic between the APs at the site.