Identity Core, persistent login is NOT persistent

Question

I'm experiencing a strange issue. I have two websites, one is a clone of the other. On website #1 (the original), logins are persistent and users aren't logged out until they choose to logout themselves.

Both websites are running ASP.NET Core 2.2

Website #1 login code:

[HttpPost("login")]
public async Task<IActionResult> Login(LoginVM model)
{
    if (ModelState.IsValid)
    {
        var signInAttempt = await _signInManager.PasswordSignInAsync(model.Email, model.Password, true, false);
        if (signInAttempt.Succeeded)
        {
            if (!string.IsNullOrEmpty(model.ReturnUrl))
            {
                return Redirect(model.ReturnUrl);
            }
            return RedirectToAction("Home");
        }

        if (signInAttempt.IsLockedOut)
        {
            ModelState.AddModelError("", _stringLocalizer["User is locked out"]);
        }
        else
        {
            ModelState.AddModelError("", _stringLocalizer["Email and password do not match"]);
        }
    }
    return View(model);
}

On website #2 (the clone), the logins aren't persistent and users are logged out after some time - I'm not sure after how long.

Website #2 login code:

[HttpPost("login")]
public async Task<IActionResult> Login(LoginVM model)
{
    if (ModelState.IsValid)
    {
        var signInAttempt = await _signInManager.PasswordSignInAsync(model.Email, model.Password, true, false);
        if (signInAttempt.Succeeded)
        {
            if (!string.IsNullOrEmpty(model.ReturnUrl))
            {
                return Redirect(model.ReturnUrl);
            }
            return RedirectToAction("Home");
        }

        if (signInAttempt.IsLockedOut)
        {
            ModelState.AddModelError("", _stringLocalizer["User is locked out"]);
        }
        else
        {
            ModelState.AddModelError("", _stringLocalizer["Email and password do not match"]);
        }
    }
    return View(model);
}

So, as you can see from above, both codes are exactly the same - both are set to true in persistence. In the websites Startup file, they're also identical:

Website #1 Startup.cs:

services.AddIdentity<ApplicationUser, IdentityRole>(options =>
{
    // Configure identity options here.
    options.Password.RequireDigit = false;
    options.Password.RequiredLength = 4;
    options.Password.RequireLowercase = false;
    options.Password.RequireNonAlphanumeric = false;
    options.Password.RequireUppercase = false;
}).AddEntityFrameworkStores<ApplicationDbContext>();

services.ConfigureApplicationCookie(options =>
{
    options.AccessDeniedPath = "/login";
    options.LoginPath = "/login";
    options.LogoutPath = "/logout";
});

Website #2 Startup.cs:

services.AddIdentity<ApplicationUser, IdentityRole>(options =>
{
    // Configure identity options here.
    options.Password.RequireDigit = false;
    options.Password.RequiredLength = 4;
    options.Password.RequireLowercase = false;
    options.Password.RequireNonAlphanumeric = false;
    options.Password.RequireUppercase = false;
}).AddEntityFrameworkStores<ApplicationDbContext>();

services.ConfigureApplicationCookie(options =>
{
    options.AccessDeniedPath = "/login";
    options.LoginPath = "/login";
    options.LogoutPath = "/logout";
});

So, my question is: How do I achieve persistent logins on website #2?

UPDATE: Users are also logged out when application pool is recycled - this also doesn't happen in website #1.