I've noticed that when you go to check your scrobbled songs in the app that you have to wait a few seconds (maybe like a minute or so) with the app open for them all to be loaded up. hopefully that solves your problem. but I too have had some trouble with the app.
If you are using Start/scrobbling tiles, the app have a bug right now that makes it don't save the songs that you heard.
If you use the app main tile to start or stop the scrobbling session everything should work fine, when you open the app it should track your songs and show up on the played page.
For more about the app you can go to the facebook page: https://www.facebook.com/pages/Metro...33911329983583 or send me an email ;)