We had isssues with several Symbol/Motorola handheld devices (MC3090, MC3190, MC9190) running on Windows CE 5 not connecting to 5GHz channels greater CH48. We tried with WLC Versions 7.4.100, 7.4.121 and 7.6.100. They connected to lightweight APs on 5 GHz channels 36, 40, 44, 48, but not to channels > CH48.
After some tests and tries, we found out enabling DFS (802.11h): "Channel Announcement" and "Channel Quiet Mode" did the trick. After enabling these options all Symbol/Motorola handhelds connected to all channels without problems.