Little time - so I shall be quick.

What PowerHA/HACMP (now System Mirror) monitors - traditionally - is the topology - for failures - and based on what has happened, it makes modifications.

1) Disks are a resource, not topology
2) diskhb network is a NON-IP network, so application service is not dependent on that.
3) HACMP does not respond - out of the box - to resource failures. You need to setup an application and/or event notification to respond to that.

Suppose, rather than both fc - you had said both/all ethernet (i.e., IP connectivity) - the result would be the same - HACMP does not move the resource group. This is because HACMP can see both nodes are operational - but NO nodes (there are only two!) can communicate with other. When no nodes can communicate via IP network HACMP concludes a "Global" network failure, and since no nodes can communicate - it does not matter where the application/service is at - no clients could communicate - so nothing is moved.

The short of it - you need to configure an application monitor that "decides", whether to move or not. A simple way to force a move (one that would work "out of the box" is a so-called panic halt (halt -q). Not really recommended of course, but it does, in an educational/test phase help demonstrate what events HACMP responds to, and what events it does not respond to.

Hope this helps.