Hello.
Our QA verified that the code below works in the Unity Editor 2021.3.31f1, 2022.3.10f1, 2023.1.17f1. If that doesn't work, try a clean build.
Thank you. :D

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This issue occurred because the UnityStreamingAssetPack designated as “fast-follow” did not complete downloading.

First, as instructed in this link(https://docs.unity.cn/2023.1/Documentation/Manual/android-asset-packs-in-unity.html), it has size limitations(https://developer.android.com/guide/playcore/asset-delivery#download-size-limits). So you should keep this in mind.

“ If the additional assets take more than 1GB of storage, Unity adds Streaming Assets into one asset pack called UnityStreamingAssetPack and adds all other assets into the UnityDataAssetPack asset pack. Uniy assigns the install-time delivery mode to the larger asset pack and assigns the fast-follow delivery mode to the smaller one.”

As mentioned in the sentences above, when I checked the generated .aab file, I could see that “install-time” was assigned to UnityDataAssetPack(around 1.13GB) and “fast-follow” was assigned to UnityStreamingAssetsPack(around 888MB).

And as you can see here(https://docs.unity.cn/2023.1/Documentation/Manual/android-asset-packs-manage.html), “Google Play automatically starts to download fast-follow asset packs after it installs the application. However, it’s possible that not all fast-follow asset packs are available on the first time the application launches.” We cannot handle this. It’s up to Google.

However, As guided in the link, you can solve the issue by adding the code like below.

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private static int _mRemainingsToDownload = 0;

private Action<AndroidAssetPackInfo> DownloadAssetPackAsyncCallback = delegate(AndroidAssetPackInfo info)
{
Debug.Log($"DownloadAssetPackAsyncCallback() name = [{info.name}], bytesDownloaded/size = {info.bytesDownloaded}/{info.size}, transferProgress = {info.transferProgress}, status = {info.status}, error = {info.error}");
if (info.status == AndroidAssetPackStatus.Completed)
{
_mRemainingsToDownload--;

if (_mRemainingsToDownload == 0)
SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);
}
};

private IEnumerator Start()
{
Debug.Log($"Start() coreUnityAssetPacksDownloaded = {AndroidAssetPacks.coreUnityAssetPacksDownloaded}, Length = {AndroidAssetPacks.GetCoreUnityAssetPackNames().Length}");
if (!AndroidAssetPacks.coreUnityAssetPacksDownloaded)
{
string[] coreUnityAssetPackNames = AndroidAssetPacks.GetCoreUnityAssetPackNames();
_mRemainingsToDownload = coreUnityAssetPackNames.Length;
AndroidAssetPacks.DownloadAssetPackAsync(coreUnityAssetPackNames, DownloadAssetPackAsyncCallback);
}
yield return null;
}

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I hope this is useful to you. Thank you.*