Are you using Sencha Mobile Packager or Phonegap? What device are you trying this on?
I'm using Sencha CMD v188.8.131.52 (on Windows 7, 32bit)
Tested on device: Huawei Honor, Android 4.0.3 (clean Android without any customization)
Native packaging finished without any errors.
Issue with picker occurred on native build of application only. If I use normal (not compiled) web-app then picker component works as expected. But in native build pressing the 'done' button of component cause opening phone dialer with entered long number.