We've taken a look at your profile settings and don't see anything that would normally restrict you from leaving feedback. Are you getting an error message when you try to leave feedback on someone's profile?
On which profiles are you trying to leave feedback? I've tested your permissions on our test server and it didn't yield an error, so I'd like to try and replicate the problem. We'd also need to know what operating system, OS version, browser, browser version, and browser add-ons you're using.
That explains it. The archives are locked and have been since our software switch to Huddler years ago. To leave feedback, you have to visit that person's profile, click "Trader History" on the left, and then you can choose to leave buyer or seller feedback for someone. As an example, here's what my page would look like after following the "Trader History" link.