XmlSerializer error deserializing to XElement in Blazor WebAssembly

I have a Blazor web project that I encountered a problem with when I published to a test server. Everything had been working when running in VS2026. I open an XML document via a stream and deserialize it to a Property object. One of the properties is a map object that contains KML data. I just want this to be an XElement I can traverse instead of trying to build out a KML data type. The (truncated) XML looks like this:

<Property><!-- Other elements --><PropertyMap><KML><!-- KML Elements --></KML></PropertyMap></Property>

And the class I am deserializing to is:

[XmlRoot]public class Property{    // Other properties omitted.    [XmlElement("PropertyMap")]    public PropertyMap Map { get; set; }}public class PropertyMap{    public XElement? KML { get; set;}}

And finally, I am deserializing it like this:

XmlSerializer serializer = new XmlSerializer(typeof(Property));Property? property = (Property?)serializer.Deserialize(fileStream);

When I publish this to IIS and run it using WebAssembly render mode, I get this error:

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: XmlTypeReflectionError, Property
System.InvalidOperationException: XmlTypeReflectionError, Property
---> System.InvalidOperationException: XmlPropertyReflectionError, Map
---> System.InvalidOperationException: XmlTypeReflectionError, PropertyMap
---> System.InvalidOperationException: XmlSerializerUnsupportedMember, PropertyMap.KML, System.Xml.Linq.XElement
---> System.InvalidOperationException: XmlConstructorInaccessible, System.Xml.Linq.XElement
Exception_EndOfInnerExceptionStack

If I switch the app to use Server render mode, the deserialization works fine. When I run it from Visual Studio using either WebAssembly or Server, it works. It only errors when publishing using WebAssembly.

I've tried publishing using both -c Release and -c Debug and it makes no difference, same error. I would assume this is because XElement has no public parameterless constructor, but in that case, why does deserialization work in the other scenarios?

In summary:

Works in VS2026 with either Blazor Server or WebAssembly.

Doesn't work when published (either IIS or running straight Kestrel) in Blazor WebAssembly. (Release or Debug)