Fix IIS Client Certificate Mapping Authentication Not Visible in Authentication Module

We have a Windows Server (IIS 10) hosting an ASP.NET WebForms application.
We need to enable Client Certificate Authentication for our website, but in IIS → Authentication, the following options are NOT visible:

Client Certificate Mapping Authentication

IIS Client Certificate Mapping Authentication

Even though the features are installed and enabled through DISM and appcmd, the IIS Manager UI still does not show them.

This issue is blocking our deployment, and we need an IIS expert who can fix it urgently.

The freelancer must:

1️⃣ Diagnose why these two IIS Authentication features do NOT appear

Client Certificate Mapping Authentication

IIS Client Certificate Mapping Authentication

2️⃣ Fix the root cause, which may include:

Missing or corrupted IIS features

Missing authentication modules (authcert.dll, authmap.dll)

Incorrect configuration in applicationHost.config

Locked or overridden sections

Missing management UI components

Incorrect delegation settings

3️⃣ Ensure the following appear under IIS → Authentication:

✔ Client Certificate Mapping Authentication
✔ IIS Client Certificate Mapping Authentication

4️⃣ Ensure client certificate authentication works

Server requests certificate

Certificate validation occurs

Website loads only when valid certificate is provided