Monkey See Achievement (Spoilers)

[ycdiRocky]

So, I wanted to do the Monkey See Achievement, climbed the whole mountain and first finished the Animal Sanctuary. Afterwards I went and got the 3 Apes, all the Cutscenes triggered and I climbed back up to the Sanctuary.
The 3 Statues were all on top, but of course I couldn't play the flute for the sanctuary anymore.
Didn't get an achievement pop up, closed the Game, saw that apparently it registered under the Steam Activity Tab but not in my personal achievement list or in Game Achievement.
Anyone else have that problem?

[ycdiRocky]

Okay, this can be closed now. A Steam restart helped for anyone who has the same problem.