No interfaces are being polled after the devices are discovered in Performance Management.
The Network Interface Monitoring Profile is not assigned to a collection that contains the devices in question.
To add the Network Interface Monitoring Profile to a Collection you:
1. In CAPC navigate to Administration > Monitored Items Management > Monitored Devices
2. In the left frame click the Monitoring Configuration drop-down then click Collections
3. Select a Collection you wish to edit (Like All Manageable Devices) then, in the bottom of the screen click Manage
4. In the left frame find Network Interface and move it into the right frame and click Save
At this point, a Metric Family update will begin and within 10 - 15 minutes, you should begin to see data for the new interfaces.