Enabling RELAY feature in nRF Connect SDK

Hi,

I have setup exactly as described in this page Bluetooth: Mesh sensor server — nRF Connect SDK 1.4.2 documentation (nordicsemi.com) ,

I can successfully read the temperature in client, but the message is not relayed to the next board,

After checking, i saw that the RELAY feature is disabled in nRF Mesh mobile app and i'm unable to Set Relay in Configuration Server too(option is blacked out)

But in code , i could see

CONFIG_BT_MESH_RELAY=y in proj.conf
CONFIG_BT_MESH_RELAY=y
CONFIG_BT_MESH_RELAY_ENABLED=y 
CONFIG_BT_MESH_RELAY_RETRANSMIT_COUNT=2
CONFIG_BT_MESH_RELAY_RETRANSMIT_INTERVAL=20     in .config
#define CONFIG_BT_MESH_RELAY 1
#define CONFIG_BT_MESH_RELAY_ENABLED 1
#define CONFIG_BT_MESH_RELAY_RETRANSMIT_COUNT 2
#define CONFIG_BT_MESH_RELAY_RETRANSMIT_INTERVAL 20     in autoconf.h
Could someone help me out...
TIA
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