[Bug] [Form Validation Context] Following the documentation example does not reproduce the expected result

[afshin29]

What happened?

I am following the Forms docs. The following example does not give me the promised result

https://microsoft.github.io/microsoft-ui-reactor/latest/forms/#validation-context

example code:

class ValidationContextDemo : Component
{
	public override Element Render()
	{
		var ctx = this.UseValidationContext();
		var (email, setEmail) = UseState("");
		var (password, setPassword) = UseState("");
		var (submitted, setSubmitted) = UseState(false);

		return VStack(12,
			SubHeading("Validation Context"),
			TextBox(email, v => { setEmail(v); ctx.NotifyValueChanged("email", v); },
				placeholderText: "user@example.com", header: "Email")
				.Validate("email", email,
					Validate.Required(),
					Validate.Email()),
			When(ctx.IsTouched("email") && ctx.HasError("email"), () =>
				TextBlock(ctx.GetMessages("email").First().Text)
					.Foreground(Theme.SystemCritical).FontSize(12)),
			PasswordBox(password, v => { setPassword(v); ctx.NotifyValueChanged("password", v); },
				placeholderText: "Min 8 characters")
				.Header("Password")
				.Validate("password", password,
					Validate.Required(),
					Validate.MinLength(8)),
			When(ctx.IsTouched("password") && ctx.HasError("password"), () =>
				TextBlock(ctx.GetMessages("password").First().Text)
					.Foreground(Theme.SystemCritical).FontSize(12)),
			Button("Register", () =>
			{
				ctx.MarkAllTouched();
				System.Diagnostics.Debug.WriteLine(
					$"email errors: {ctx.GetMessages("email").Count()}, " +
					$"password errors: {ctx.GetMessages("password").Count()}, " +
					$"valid: {ctx.IsValid()}");
				if (ctx.IsValid()) setSubmitted(true);
			}).IsEnabled(!submitted),
			When(submitted, () =>
				TextBlock("Registration successful!")
					.Foreground(Theme.SystemSuccess).SemiBold())
		).Padding(24)
		.RequestedTheme(ElementTheme.Light)
		.Backdrop(BackdropKind.Mica);
	}
}

When I click the "Register" button, the form gets submitted successfully without any error.

Steps to reproduce

1. Follow the get started guide to setup the Reactor (preview 15)
2. Follow the validation context example from docs (https://microsoft.github.io/microsoft-ui-reactor/latest/forms/#validation-context)

Reactor version / commit

0.1.0-preview.15

Platform

x64

.NET SDK version

10.0.401

Windows version

Windows 11 25H2 (26200.9457)

Windows App SDK version

2.5.1

Logs / stack trace

Confirmation

• I have searched existing issues and this isn't a duplicate.
• This bug reproduces against the current main branch (or I've noted otherwise above).