ContentInsetLeft not working on toolbar

Question

I searched for a solution to this problem on stackoverflow almost all day, but I could not find a solution.

I have a custom toolbar created as follows:

<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#00a7e0" android:contentInsetLeft="0dp" android:contentInsetStart="0dp" app:contentInsetLeft="0dp" app:contentInsetStart="0dp" android:contentInsetRight="0dp" android:contentInsetEnd="0dp" app:contentInsetRight="0dp" app:contentInsetEnd="0dp"> 

Now I have a small left margin in the toolbar, for example:

Now you can remove this left margin with the contentInsetLeft (or -Start), which I already included in the xml toolbar. Unfortunately, left margin is still present on my Samsung S7 running Android 6.0. I tried all possible solutions, but this has not changed. Oddly enough, the left margin disappears when you launch the application on an older device with Android 4.1.2.

Does anyone have a solution?

EDIT: Perhaps I should mention that I use the Ionic Framework for the core application. I am working on an Ionic plugin, which is a native android.