Patrick,
Spectrum reads the ipAddrTable and ipAddressTable mibs to determine the ip addresses configured on the device and the interfaces where those ip addresses are configured. For the interfaces where those ip addresses are configured, Spectrum reads the ipAdEntIfIndex attribute from the ipAddrTable and the ipAddressIfIndex attribute from the ipAddressTable.
Please use MIB Tools to check if these devices are populating these tables and attributes.
Joe