Spotify Pause/Play Skip Keyboard Shortcuts

I'm all new to BetterTouchTool. One of the first things I did was to set in macOS "Use F1, F2, ..." and then I mapped each key in BTT to take over the F1-F12 keys to function just like the default media keys would. All works like a charm but the Skip & Pause/Play buttons don't do anything. I primarily want them to work with Spotify but at the moment they don't work with iTunes, QuickTime or anything else.

Probably I'm making some rocky mistake here. I really appreciate any tips and pointers you guys could give me!