How do I get FilePicker to return a non-null result on MacCatalyst?

Question

Maui Workload 9.0.14/9.0.100
SDK 9.0.200
XCode 16.3 (16e140)
Mac OS Sequoia 15.3.2
Visual Studio Code 1.98.2 (Universal)

I am developing a MAUI App that needs to run on Windows, MacOS and iOS (iPad only). I am trying to get FilePicker.Default.PickAsync() to return a non-null result on a Mac. It returns a non-null result on Windows and using the iPad simulator. On MacCatalyst, FilePicker.Default.PickAsync() displays the correct file selection dialog. I navigate to my Downloads folder, select the file I want to use, and click [Open]. The result from FilePicker.Default.PickAsync() is always null.

Code snippet that works on Windows and iOS, but returns null on MacOS (it's inside a try/catch block):

        PickOptions options = new PickOptions();
        options.PickerTitle = "Select a SmartRun 4 run file";
        var runFileType =
            new FilePickerFileType(
                new Dictionary<DevicePlatform, IEnumerable<string>>                    
                {
                  { DevicePlatform.iOS, new[] { "public.comma-separated-values-text" } },
                  { DevicePlatform.WinUI, new[] { ".csv" } },
                  { DevicePlatform.MacCatalyst, new[] { "public.comma-separated-values-text" } }
                });
        options.FileTypes = runFileType;
        FileResult? result = await FilePicker.Default.PickAsync(options);
        if (result != null)
        {
            // I get here on Windows and iOS. I never get here (no exceptions) on MacOS
            // as result is always null.

My MacCatalyst Entitlements.plist file contains the following entries as noted on the .NET MAUI FilePicker information page:

        <key>com.apple.security.assets.movies.read-only</key>
        <true/>
        <key>com.apple.security.assets.music.read-only</key>
        <true/>
        <key>com.apple.security.assets.pictures.read-only</key>
        <true/>
        <key>com.apple.security.files.downloads.read-only</key>
        <true/>
        <key>com.apple.security.files.user-selected.read-only</key>
        <true/>
        <key>com.apple.security.personal-information.photos-library</key>
        <true/>

I've also added the following entries to Entitlements.plist in a desperate attempt to get a non-null result:

        <key>com.apple.security.files.downloads.read-only</key>
        <true/>
        <key>com.apple.security.files.user-selected.read-only</key>
        <true/>

I have the following entries in both the iOS and MacCatalyst Info.plist files. Apple's documentation indicates they should be present:

	<key>NSDownloadsFolderUsageDescription</key>
	<string>The Downloads folder is where your browser saves files.</string>
	<key>NSDocumentsFolderUsageDescription</key>
	<string>The Documents folder is where you might copy files from some elsewhere.</string>

If I don't use a FilePicker and just pass the full file path (in my Downloads folder) to File.ReadLines(), the program successfully reads the file. I therefore know the file can be accessed within the program. I just need FilePicker to work. What am I missing? Please help.