Webviewer displays blank

I added WebViewObject.cs and a custom webview manager to a game object, however it only displays a solid dark gray. Here's my webview manager script. Tested on my Android 12 device:

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class WebViewManager : MonoBehaviour
{
    public string Url = "https://google.com";
    public WebViewObject webViewObject;

    IEnumerator Start()
    {
        int screenWidth = Screen.width;
        int screenHeight = Screen.height;
        webViewObject.Init((msg) =>
        {
            Debug.Log($"CallFromJS[{msg}]");
        });

        webViewObject.SetMargins(screenWidth / 4, screenHeight / 4, screenWidth / 4, screenHeight / 4);
        webViewObject.SetVisibility(true);

#if !UNITY_WEBPLAYER && !UNITY_WEBGL
        webViewObject.LoadURL(Url.Replace(" ", "%20"));
#else
        webViewObject.LoadURL("StreamingAssets/" + Url.Replace(" ", "%20"));
#endif

        yield break;
    }
}

Start by reproducing the blank WebView on the reported Android 12 device using the provided WebViewManager, then read WebViewObject.cs around Init, SetMargins, SetVisibility, and LoadURL. Done means the configured URL renders instead of a solid dark-gray view.