The key to success in this game is to utilize your soldier towers effectively to slow the enemies down. Once you can upgrade them to Paladins, ensure you get their shield and healing abilities. Combine them slowing down a wave and creating a crowd with Meteor Swarm for very effective clearing.
The problem with the infinite loading is that on subsequent loads, it doesn't retrieve badge data, it just goes straight to the processing and hangs there. As mentioned, clearing the cache will have the app reretrieve badge data. Hopefully this is a quick and easy fix that Senesis can do.
That's a bad thing?