Ionic Icons and Android

It seems the icons at the bottom, and even background images don’t show up when I use Cordova and ant debug install
to create an android application.

I had this in my CSS:
background: url(‘img/icon1.png’)

It show up with Ionic, on my website, but not on Android. Later on, I notice the native icons from an application created with Ionic does not work either.

It is not an Android bug because I have another application without Ionic that works fine with a CSS like that one.