Device Loopback IP address used to discover a device in Smarts IP is not being used to set the SNMPAddress variable
This behavior occurs when the IP address in question is an HSRP IP address part of HSRPGroup. Smarts does not assign HSRP IP addresses to the SNMPAddress variable unless there are no additional IP addresses available in the device's IP address list to be used. If the device has more IP addresses available, a different IP is being used to set SNMPAddress, not the loopback address used to discover the device.
No fix is available or required. Smarts IP is functioning as designed.