Without clear troubleshooting to say it's not your client, you can try using published details on band-steering options. I can say however, that the band-steering in 9.8 standalone AP code did not have all commands implemented correctly (ER-2078).
https://support.ruckuswireless.com/answers/000002508
Here's the command syntax that should work:
rkscli: set band-balancingparameter errorUsage: set band-balancing {options} -- {|all} {enable|disable} -- {|all} rssi -- percent -- minsta -- mesh-ap {enable|disable}
rkscli: set band-balancing wlan9 enableOKrkscli: get band-banlancing wlan9Command is not recognized: get band-banlancing wlan9
rkscli: get band-balancing wlan9Band Balancing: wlan9: Enable RSSI Threshold: wlan9, 20 Band Balancing Percent: wifi1, 0 MinSta Threshold: AP, 10 Under Mesh AP : OffOKrkscli: