null value for CustomEvent in Blazor wrapper for native JS Web Component

We are attempting to build a Blazor wrapper for our native Javascript web component library.

Our input emits a custom event valueChange whenever the user changes the value of the text field (i.e.: types/deletes stuff in it). We want to capture this event and retrieve the detail property in the CustomEvent, which contains the current text box's text:

library-input.js:

#updateValue(value) {    // ... updating the native `value` attribute    const valueEvent = new CustomEvent("valueChange", {        detail: this.#value,        bubbles: true,    });    this.dispatchEvent(valueEvent);}

libraryInput.razor:

@inject IJSRuntime JSRuntime@namespace BlazorWrapperForLibrary@using System.Text.Json<lib-input @ref="libInput" @onvalueChange="ValueChanged"></lib-input>@code {    private ElementReference libInput;    private const string JAVASCRIPT_FILE = "/js/library-components.js";    private const string INTEROP_FILE = "/js/lib-input.interop.js";    private IJSObjectReference? Module { get; set; }    private IJSObjectReference? Interop { get; set; }    [Parameter]    public string? Value { get; set; }    [Parameter]    public EventCallback<InputValueChangeEventArgs> ValueChanged {get; set;}    protected override async Task OnAfterRenderAsync(bool firstRender)    {        if (firstRender)        {            Module = await JSRuntime.InvokeAsync<IJSObjectReference>("import", JAVASCRIPT_FILE);            Interop = await JSRuntime.InvokeAsync<IJSObjectReference>("import", INTEROP_FILE);        }    }}

CustomEvents.cs:

public class InputValueChangeEventArgs : EventArgs{    public string? detail { get; set; }}[EventHandler("onvalueChange", typeof(InputValueChangeEventArgs), enableStopPropagation: true, enablePreventDefault: true)]public static class EventHandlers{}

Counter.razor:

@page "/counter"<LibInput Value="newValue" ValueChanged="@((InputValueChangeEventArgs value) => InputChanged(value))"></LibInput>@code {    private string newValue = "undefined";    private void InputChanged(InputValueChangeEventArgs value)    {        Console.WriteLine(value.detail);    }}

• When I add an event listener for the valueChange on the document I can see the detail property is filled successfully.
• When I put a breakpoint in the JS for Blazor in the devtools (onGlobalEvent(e) in the blazor.server.js) I can also see the detail property filled in.
• When I inspect the Web Socket Messages I see ......BeginInvokeDotNetFromJS..1..DispatchEventAsync..I[{"eventHandlerId":7,"eventName":"valueChange","eventFieldInfo":null},{}]. I'm not sure if eventFieldInfo: null has anything to do with this.
• When I put a breakpoint in the InputChanged() method in the Counter.razor file, the detail property is null.