When using the same SSID on 2.4 and 5hgz radios, I've had many Mac's drop their connection and constantly scan for wifi. The fix usually is to turn wifi off and then back on again on the Mac and signal comes back. This has been on many different sites that I install. iPads, iPhones, PC's and other devices all seem to be unaffected, just Mac's. Apple had an issue early on when they released their AC card but this issue has popped up here and there for quite a while. Once I switched to separate SSID's, the problems stopped. I'm just assuming Mac's have low quality radios.
This isn't specific to Ruckus, I've had the same results with other brand WAP's as well.