Can't find view in bottom sheet with Espresso

I have a Fragmant that contains a CoordinatorLayout with two children: a MapView (Google Maps API) & a RelativeLayout, this last layout contains some buttons that I want to test using Espresso.

So here's my test:

@Test
fun randomButtonTest() {
    try {
        Thread.sleep(2000)
    } catch (e: InterruptedException) {
        e.printStackTrace()
    }

    // Find the button and perform a click
    val appCompatImageButton = onView(
            allOf(withId(R.id.random_poi), withContentDescription("Random Point of Interest"),
                    withParent(withId(R.id.design_bottom_sheet)),
                    isDisplayed()))
    appCompatImageButton.perform(click())

}

And here is my layout (I have removed all layout related parameters for visibility):

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://ift.tt/nIICcg"
    xmlns:app="http://ift.tt/GEGVYd"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.google.android.gms.maps.MapView
        android:id="@+id/mapView"/>

    <RelativeLayout
        android:id="@+id/design_bottom_sheet"            
        app:behavior_hideable="true"
        app:layout_behavior="@string/bottom_sheet_behavior">

        <ImageButton
            android:id="@+id/up_arrow" />  

        <ImageButton
            android:id="@+id/random_poi"
            android:contentDescription="@string/random_poi"/>

    </RelativeLayout>


</android.support.design.widget.CoordinatorLayout>

I get the following error when launching my instrumented test:

android.support.test.espresso.NoMatchingViewException: No views in hierarchy found matching: (with id: kade.com.accio:id/random_poi and with content description: is "Random Point of Interest" and has parent matching: with id: kade.com.accio:id/design_bottom_sheet and is displayed on the screen to the user)

Is that because my button is in a bottom sheet? Why can't I find this view?