Solved: not getting gems from cogs and machine master
So I love the cogs and machine master games and have gone through them with all of my vikings, but as we've all noticed sometimes our efforts are not rewarded!
Here's the secret; when you start either game, be sure to exit at least once before completing all the levels. Every time I did so I won my gems; and the times I didn't I lost them. And of course, be sure to check and make sure you got all 3 stars on each level. That one got me once or twice :D
If you've already gone through all the levels and got 3 stars, but no gems, just contact the support team. Brynjolf was able to help my sister out with it
Hope this helps!