Ionic app intermittent problem on Android KitKat

I have an app that has been in production for about a year. I am having an intermittent issue that seems to arise only on Android and 99% of the time on 4.4.x ( kitkat ). The issue happens during the registration process. The user gets through registration ( App uses Firebase Auth ). The user gets registered and the success callback is run and then the app hangs.

The app has thousands of users and NOT every kitkat user encounters this issue. I have test the app on the same device and OS version where I have logged users having problems. I can not recreate this issue.

Has anyone seen anything remotely like this and/or suggestions for finding resolution.

( App uses Ionic 1.2.4, cordova 5.1.1 )