I’m still on DP6 (slow internet), where everything works.
Most of my apps build the framework from source as a subproject, but I think it should work the same with built frameworks. The relevant checkbox is called “Code Sign On Copy” and shows up in the Copy Files build phase in the Build Phases tab.
Maybe make a new blank Cocoa Application project and add the framework to that, see if it works as it should, then see if you can spot the difference between that and your projects?
Sorry not to be more useful – the Apple docs or dev forum may make more sense than us…