Not sure if directly related to the extension, so I post in this category.
While I have loaded the extension “TaifunBattery” (Battery Manager extension. Version 1a as of 2016-08-11 for App Inventor version nb150 and Companion version 2.38.) and made a simple button that will change text in a label with level from battery, Thunkable Live does not work. It is stuck in:
Sending assets/external_comps/com.puravidaapps.TaifunBattery/classes.jar to companion…
That said, if I build an apk, everything works as expected.