The controller version you are running does not support H320 please apply the patch and upgrade the zone to the firmware 18.104.22.1689:
The SmartZone new AP Bundle process has been developed to:
1) allow existing SmartZone controllers to add new AP model support, or
2) apply important bug fixes before the next Maintenance Release with these built-in.
This new AP Bundle will add H320 model AP support, and important bug fixes to SmartZone 22.214.171.124.269 (MR1) Controllers.
You must upgrade to this version of vSZ-E or SZ-100, if running previous versions.
After application, connected zone APs will reboot, and come back up on 126.96.36.199.469 build version.
Refer to release notes SmartZone 3.5.1 (MR1) AP Bundle for H320 (b469) Release Noteshttps://ruckus-support.s3.amazonaws.com/private/documents/1920/b-Sz351GaReleaseNotesForH320-20170721...
Principal Technical support Engineer