In Network Insight for ASA, your Node Details for ASA page gives you a resource called 'Bandwidth'. This resource is empty by default, it is populated when you "favorite" an interface in that node's interfaces page. The Bandwidth resource has a maximum allowed number of interfaces that can be added - three. I think NPM should automatically "favorite" your interfaces, or at least add them to this resource, if your ASA only has three or fewer interfaces being managed. Here's some screenshots:
The empty resource

The interfaces page, where you "favorite" interfaces
