We hve this problem.
We have a network, working properly since 2 years, of 15 autonomous AP (mix of 1200, 1300 and 1400).
One of them is WCS master, we have configured few ssidd.
Now we are migrating to LAP and WLC 4402, all seems to work properly in lab environment, but when we have migrated AP in production, problems appear :(
In particular, for one ssid configured on old AP for WPA/TKIP auth, some devices go well on new architecture (on WLC we have configured a ssid with same name and same parameters), but many of them fail.
Watching in Monitor Clients I can see some of them always in Probing status, with Unknown SSID, other associated to correct SSID but not Authenticated.