Wireless Controller
Dedicated Wi-Fi control and management for high density and mobility
Article Id 189412
This article explains why SSID may disappear when ARRP was enabled on the controller.

Meru controller, 8.1 and later.

ARRP is one of the new features which has introduced in Firmware 8.1 and later, where in APs scan the best available channel to operate and the controller in turn allocates these channels to AP radios.

ESS profile with virtual cell configuration will no longer be broadcasted by APs when ARRP is enabled as virtual cell configuration is a single channel configuration. 

The RF virtualization mode must be changed in every ESS profile to native cell in order to make any 802.11ac AP to broadcast the SSID.

Note that once ARRP is disabled all the ESS profiles remain unchanged and APs will continue to broadcast the SSID’s in native cell configuration only.