Override PasswordSignInAsync in Custom SignInManager (ASP.NET Core 2)

Question

A funny thing happend to me. So funny, I'm still out of control.

Short story: inspired by https://www.stevejgordon.co.uk/extending-the-asp-net-core-identity-signinmanager I created a custom SignInManager with an override of the PasswordSignInAsync method. Background of this requirement is to have a second log in page (with a PIN). However, when I'm trying to login from the new page (LoginPin.cshtml), the PasswordSignInAsync is not hit.

And here's the funny thing: when I do the same from the Login.cshtml page it is hit!

Long story:

public class AuditableSignInManager<TUser> : SignInManager<TUser> where TUser : class
{
    private readonly UserManager<TUser> _userManager;
    private readonly ApplicationDbContext _db;
    private readonly IHttpContextAccessor _contextAccessor;

    public AuditableSignInManager(UserManager<TUser> userManager, IHttpContextAccessor contextAccessor, IUserClaimsPrincipalFactory<TUser> claimsFactory, 
        IOptions<IdentityOptions> optionsAccessor, ILogger<SignInManager<TUser>> logger, ApplicationDbContext dbContext, IAuthenticationSchemeProvider schemes)
        : base(userManager, contextAccessor, claimsFactory, optionsAccessor, logger, schemes)
    {
        _userManager = userManager ?? throw new ArgumentNullException(nameof(userManager));
        _contextAccessor = contextAccessor ?? throw new ArgumentNullException(nameof(contextAccessor));
        _db = dbContext ?? throw new ArgumentNullException(nameof(dbContext));
    }

    public override async Task<SignInResult> PasswordSignInAsync(TUser user, string password, bool isPersistent, bool lockoutOnFailure)
    {
        //skipped for readability reasons 
var result = await base.PasswordSignInAsync(user, password, isPersistent, lockoutOnFailure);
    }
}

Startup.cs & Dependency Injection:

services.AddScoped<SignInManager<ApplicationUser>, AuditableSignInManager<ApplicationUser>>();

Login.cshtml.cs

public class LoginModel : PageModel
{
    private readonly SignInManager<ApplicationUser> _signInManager;
    private readonly ILogger<LoginModel> _logger;

    public LoginModel(SignInManager<ApplicationUser> signInManager, ILogger<LoginModel> logger)
    {
        _signInManager = signInManager;
        _logger = logger;
    }

    // skipped

    public async Task<IActionResult> OnPostAsync(string returnUrl = null)
    {
        var result = await _signInManager.PasswordSignInAsync(Input.UserName, Input.Password, false, lockoutOnFailure: false);
    }
}

LoginPin.cshtml.cs

public class LoginModelPin : PageModel
{


private readonly SignInManager<ApplicationUser> _signInManager;
    private readonly ILogger<LoginModelPin> _logger;

public LoginModelPin(SignInManager<ApplicationUser> signInManager, ILogger<LoginModelPin> logger)
{
    _signInManager = signInManager;
    _logger = logger;
}

public async Task<IActionResult> OnPostAsync(string returnUrl = null)
{
    var result = await _signInManager.PasswordSignInAsync(usrPwd, usrPwd, false, lockoutOnFailure: false);
}
}

To be honest: it is not funny anymore. Could someone point me to the right direction?

Many thanks in advance.

N.