Ionic-cordova-qrscanner black screen (android kitkat)

Ionic Framework ionic-v3
1

not able to see camera, black screen appearing.
checked the chrome inspect logs, says we have the camera permission and everything, background is also transparent till html(checked that thoroughly), just the screen appears black. seems like camera has not started.

any hints? should I use ionic android permissions?

info

working with crosswalk and android@6.3.0

Ionic:

ionic (Ionic CLI) : 4.1.1 (~/.nvm/versions/node/v9.8.0/lib/node_modules/ionic)
Ionic Framework : ionic-angular 3.9.2
@ionic/app-scripts : 3.2.0

Cordova:

cordova (Cordova CLI) : 8.0.0
Cordova Platforms : android 6.3.0
Cordova Plugins : cordova-plugin-ionic-keyboard 2.1.2, cordova-plugin-ionic-webview 2.1.4, (and 13 other plugins)

System:

Android SDK Tools : 26.1.1 (/Android)
NodeJS : v9.8.0 (/.nvm/versions/node/v9.8.0/bin/node)
npm : 5.8.0
OS : Linux 3.13

2

have you got any other plugin which tries to access camera as well?

I am experiencing similar issue when trying to use cordova-camera-preview with cordova-plugin-qrscanner.
In my case it seems like preview of camera-preview plugin is blocking preview for qrscanner.
As of now i have no solution.