I am unable to bring up the camera using Appcelerator in Android 6.0 using Ti.MEDIA.ShowCamera(...). I'm doing a basic Proof of Concept app for Android and iOS. It works fine in iOS and on Android 4, 5, and 5.1. I'm using the latest Appcelerator SDK: 5.1.2.GA and have tested on an actual Nexus 6 running 6.0.0 and also on the Genymotion Nexus 6 Emulator running 6.0.0.
Well, I think that you have been hit by the new permissions for Android 6.0. You can see more in the Titanium 5.1.0 sample app - specifically in the permissions.js file
Struggling with this myself at the moment :-)
Edit:
I have not been able to use any emulators (Genymotion or Android emulators coming with Android Studio 2.0 beta) to work correctly with the new permissions etc. for Android 6.0. I had to buy a device the other day - and now I have fixed and tested the issues in my app :-)
I did use several days to try and get a decent test environment using emulators. But apparently all of that is a little too early for Android 6.0 :-(
/John