Not able to ping devices to the spoke site from the hub side even though the SVR tunnel is up.

• peer path traffic can only be initiated in 1 direction spoke->hub
• SSR spoke device is behind NAT (Hub has public IP)
• hub-spoke initiated traffic fails

Configure your wan adjacency mode as "outbound-only" for the device behind NAT connection 

Documentation:

"Set to outbound-only if the adjacency is behind a NAT device."

https://www.juniper.net/documentation/us/en/software/session-smart-router/docs/config_reference_guide#adjacency