I can't seem to achieve this. My goal is to raise the agility of 8 dwellers. I got it to 7, and that was after raising at least 20 dwellers agility. Now it won't finish. Any ideas? I could skip it but why should I?

Are you using eight different dwellers? Raising one dweller's agility by more than one point doesn't count toward the objective.

That could be it! Thanks!