The app isn't working on any 4.4 device we've tried so far. Issue is in the AOS missing some OTG support structure. Other developers we talk to are also fighting the issue and working with Google to fix the problem.

You can clearly see it being an AOS issue on certain devices. My Samsung Tab2 10.1 for example. App runs great on 4.1.2 , but if I install 4.2.2 it won't work.

It was supposed to be a "Security" update but they've yet to complete the project is what we're told.