I would recommend to open support ticket so we can get SNMP walk of your Cisco device. IF-MIB should be supported here and you should be able to see Interfaces for your Cisco device.
Having the same issue on NPM10.6. I upgraded from 10.2 which was getting the interface stats. Now on NPM10.6 the device which is already in the database from the previous version is showing the previously added interfaces under node details. The strange part is that when i go to node management & click list resources i only see CPU,Memory,Routing & Topology, no interfaces.