7.4.7 - Interface not showing up in Local-In Policy source interface list

Greetings all,

I was looking at the options available for local-in policies and defined source interfaces and noticed that some interfaces are not listed.  These appear to be interfaces being used for WAN purposes, but even when switching their roles to 'undefined' they will not show up as available interfaces.  Anyone know what conditions may make an interface unavailable for use in local-in policies?