Minimal reproduction project demonstrating two critical bugs in .NET MAUI Maps on Android.

The Microsoft.Maui.Controls.Maps.Map control on Android has two bugs where MAUI object state does not sync to the native Google Map:

1. BUG 1: MapElements.Clear() removes items from the collection (Count becomes 0), but the native Google Map still displays the polygon visuals.

2. BUG 2: Changing polygon properties (FillColor, StrokeColor) updates the MAUI object, but the native Google Map polygon is not updated to reflect the changes.

Both bugs appear to be in the MapElementHandler which is not forwarding changes to the native platform.

1. Run the app on Android
2. Tap "1. Add 3 Polygons" - three colored polygons appear on the map
3. Tap "2. Clear()" - status shows "Count = 0"
4. Observe: Polygons are still visible on the map despite Count being 0

1. Run the app on Android
2. Tap "1. Add Polygons" - three colored polygons appear
3. Tap "2. Set Alpha=0" - this sets FillColor.Alpha to 0.0 on all polygons
4. Tap "3. Diagnostics" - console shows FillColor.Alpha = 0.00 for all polygons
5. Observe: Polygons are still visible despite MAUI property being 0

The MAUI objects are updated correctly. The bug is that changes are not propagated to the native Google Map.

After adding polygons, then setting alpha to 0:

=== DIAGNOSTICS ===
MapElements.Count: 3
Map.Handler: MapHandler
[0] Polygon:
    FillColor: R=1.00 G=0.00 B=0.00 A=0.00   <-- Alpha is 0, but polygon still visible!
    StrokeColor: R=0.55 G=0.00 B=0.00 A=0.00
    Handler: MapElementHandler
[1] Polygon:
    FillColor: R=0.00 G=1.00 B=0.00 A=0.00
    ...

• #18234 - Android Opacity not set at startup
• #22510 - Multiple polylines corruption (handler state issues)
• #9759 - Polyline Fill not working (fixed in .NET 7/8)
• #1711 - Map elements never render (Windows/CommunityToolkit)

• .NET 9.0 SDK
• Visual Studio 2022 or VS Code with MAUI workload
• Android SDK
• Google Maps API key from Google Cloud Console

1. Get a Google Maps API key and enable "Maps SDK for Android"
2. Replace the API key in Platforms/Android/AndroidManifest.xml:

   <meta-data android:name="com.google.android.geo.API_KEY" android:value="YOUR_KEY_HERE" />

cd MauiMapOpacityDemo

# Build for Android
dotnet build -f net9.0-android

# Run on Android emulator/device
dotnet build -t:Run -f net9.0-android

We tested many workarounds - none successfully clear the "ghost" polygons via MAUI APIs:

The workaround described in #30097 sets Visible = false and calls Remove() on elements. This works because it accesses native Google Maps objects directly, not the MAUI MapElement abstraction.

MAUI's MapElement inherits from Element (not VisualElement), so it has no IsVisible property. To use the #30097 workaround, you must write a custom handler that accesses native platform objects.

• .NET MAUI 9.0.0
• Microsoft.Maui.Controls.Maps 9.0.0
• Tested on: Android emulator (API 34)
• Target Framework: net9.0-android