MVC Razor not rendering Checkbox Value in a Partial - Razor Bug?

I have the following:

Model

public class MyPartialModel
{
     // Note, this is NOT nullable
     public bool MyBoolean { get; set; }
}

Partial

@model MyPartialModel

@using Html.BeginForm(...) {
    @Html.CheckBoxFor(m => m.MyBoolean)
}

Partial Invocation From View

@Html.Partial("MyPartial", new MyPartialModel());

My expected result based on the same syntax in a regular view is:

// Main checkbox
<input id="MyBoolean" name="MyBoolean" type="checkbox" value="false">
// Hidden input rendered by Razor
<input name="MyBoolean" type="hidden" value="false">

My actual result is:

// Main checkbox - note the absence of ="false" on the value
<input id="MyBoolean" name="MyBoolean" type="checkbox" value>
// Hidden input rendered by Razor - note, again, the absence of ="false" on the value
<input name="MyBoolean" type="hidden" value>

The same appears (no value assignment) when I force the value in my model to true as shown here:

public class MyPartialModel
{
     // Note, this is NOT nullable and initialized to true
     public bool MyBoolean { get; set; } = true;
}

Is this a bug or am I missing something?