Whenever you tap on the Store, the game needs to connect to the Appstore or Playstore to load all the offers. If for some reason it's unable to connect, which there could be any number of reasons why it fails, it'll appear to just be loading forever.
Technically, we designed it so that it will eventually load, but only the Free offers or offers you can purchase with Theonite. If it happens again, I recommend setting the phone aside and coming back after a few minutes to see if it finally loaded anything.