Steam Question: Missing Achievement Glitch, what's the fix?

[Ifeno]

Hi guys!  I just reached Eagle (MR 16) and got the corresponding achievement on steam.  When I went to look at what achievements I was missing, I saw that I am still missing the Gold Hunter (MR 15) achievement.  Does anyone know how I can get this fixed?

[Kraantion]

Steam Achievement Manager

[Myscho]

There is one program called SAM (Steam achievement manager), which you can unlock all achievements for game, not only bugged