IssueTracker

ConstraintLayout version: 2.0.0-beta4
Android API version: 22

Steps to reproduce:

1. Run the app on an emulator/device with API 22 (emu reproduces every time)
2. A list of elements should be shown

The list isn't shown.

What I noticed is that having a structure like this:

<?xml version="1.0" encoding="utf-8"?>
<layout>
    <data>
        <import type="android.view.View" />

        <variable
            name="loading"
            type="Boolean" />
    </data>


    <RelativeLayout 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="match_parent"
        tools:context=".MainActivity">

        <ProgressBar
            android:id="@+id/loadingStatus"
            style="?android:attr/progressBarStyleLarge"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:visibility="@{loading ? View.VISIBLE : View.GONE }" />

        <TextView
            android:id="@+id/text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Title bar"
            android:textSize="38sp"
            android:layout_alignParentTop="true" />

        <androidx.core.widget.NestedScrollView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_below="@+id/text"
            android:layout_alignParentBottom="true"
            android:visibility="@{loading ? View.GONE : View.VISIBLE}">

            <androidx.constraintlayout.widget.ConstraintLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                .... some views here


            </androidx.constraintlayout.widget.ConstraintLayout>

        </androidx.core.widget.NestedScrollView>

    </RelativeLayout>
</layout>

And quickly changing the value of  "loading" to false (50ms in the attached repro project) -> true, will fail to show the inner NestedScrollView

This happens on Android API 22 only, on more recent APIs it works fine.

Changing the top level ConstraintLayout to be a RelativeLayout fixes the issue (see activity_main_relative.xml and inside MainActivity.kt in the repro zip)