This is a cosmetic bug in the GUI. I spotted the same in our test lab; every AP will show as being on the same 2.4GHz channel (normally the channel that the master AP is on).
If look at the 2.4GHz channel in each AP's CLI, you can see that the APs are not all on the same channel, but are distributed between the channels. You could also use something like inSSIDer to see that the APs are on different 2.4GHz channels.
I logged this with Ruckus support a few weeks back and they have logged it as a bug.