How do you level up someone?

[Stars-N-Stripes]

I have a message at the top one of my people can level up, when I try to click on something to level them up nothing happens whether I double click or highlight and click OK. This person is not part of a console so only the last option is available "Unifier" , but I have no idea how to select it. The + sign wont go away even though I selected it. The only thing I can guess is it looks like they already have that trait so it won't apply and level up?

Here is a screenshot
https://ibb.co/MZdFbhZ

[CrUsHeR]

Yeah there are some leader bugs. Sometimes you hire a new leader and he isn't in your active roster, sometimes they level up but you cannot give them a perk.

Also the levelup screen may show a version of the trait the character already has, e.g. the free scientist from "diamon in the raw" already had Genius II when he was recruited, while the levelup trait selection showed the exact same trait.

Or scientists get to roll the Scout trait, which only works when commanding military fleets.

[Druitt]

You're clicking on the circle-plus icon? I had a bug just now where I could to that, but then when it gave me two traits to choose it would not accept the first trait, only the second one. So I took the second one.

I think I also had another bug with leveling and one location allowed me to do it (maybe the Leader tab), while another did not.