Can't clear contamination with legion

[Yzman]

I am trying to get the achievement...there is contamination there...a worker has the option...I can't seem to find the option for the legion though. Saw a video of someone doing it too...and I don't the button.

Why does nothing in this game work? Am I being dumb and missing the button somewhere? I just want the dumb achievement.

My save file is attached. Can anyone figure out what I am doing wrong?

 

[Yzman]

Found the issue...I didn't HARD BUILD that legion so he didn't have the option. Unfortunately my only legion that does have the option it appears is now a musketman...and I confirmed he did not give me the achievement. Not having the features of a unit just because you upgrade into it seems like a flaw to me.