I was trying out the new samples from the GitHub Repository with ARFoundation 4.0 preview 3 in Unity 2020.1b7 on a Mac OSX 10.15.4 building for an Android 10 (Huawei P30Pro).
While things like just a ARSessionOrigin-Camera works and also the PointCloud-Samples, I only get a Black Background when I add/enable the “ARTrackedImageManager”-Script.