We are having the exact issue described in Microsoft KB2934842:
The range of ports is not displayed when a Windows Firewall rule defines a local port range
However, the article applies only to Windows Server 2008 R2 (Win7) and Windows Server 2012 R2 (Win8.1). We're running Windows Server 2012 (Win8.0), and neither hotfix that's prescribed is compatible with what we're running.
The article also fails to explain whether the issue is merely a superficial display problem, or whether the GPO will not apply the port ranges that don't appear in the Settings pane of the GPMC.
We're desperate to get out a new, large Firewall GPO, but we need to fully understand what may or may not be working.
Can anyone shed some light on this for us?