I see the problem, it's the counter on the "done choosing" button -- Courtier "requires" you to pick 3 but Elder's additional option is not required. The counter on that button counts down the required picks but it just doesn't look like you can pick another option.
So this isn't a bug, it's just an interface issue -- until I was told that I could pick that fourth option anyways, it looked like I couldn't even pick it. I think the counter should have the maximum allowed options on it rather than the number of required options. Or maybe a range if you can get that to look good?