Strange shadow behavior during `alpha` animation

Question

Have recycler with CardView items. When screen open - I start alpha animation on recycler :

recyclerView.animate().alpha(1f).setStartDelay(300).start()

Recycler item:

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginStart="20dp"
    android:layout_marginTop="6dp"
    android:layout_marginEnd="20dp"
    android:layout_marginBottom="6dp"
    app:cardCornerRadius="10dp"
    app:cardElevation="4dp">
...
</android.support.v7.widget.CardView>

Problem that while this animation running the shadow of CardView directed to the up but when animation ends shadow change direction to the bottom (as normal)

Problem was found only on Android 9.

P.S. sorry for my english)

Answer 1

Found a workaround. Make sure the alpha-animation targets on CardView itself instead of its parent and its parent's alpha must be 1F. This work in my case. Hope it can help you too.

Answer 2

I have found a partial fix,

If you add android:layerType="hardware" to the parent view the shadow no longer flips direction.

The down side is the shadow permanently points in the wrong direction.