How to get additional claims on client side in identity server 4?

In my identity server's Startup.cs file, I have server configured as below. I am using asp.net identity for user management.

services.AddIdentityServer()
                .AddDeveloperSigningCredential()
                .AddInMemoryPersistedGrants()
                .AddInMemoryIdentityResources(Config.GetIdentityResources())
                .AddInMemoryApiResources(Config.GetApiResources())
                .AddInMemoryClients(Config.GetClients())
                .AddAspNetIdentity<ApplicationUser>();

services.AddTransient<IProfileService, ProfileService>();

My IdentiyResources are as follow. Here I want to return extra claim as IS_Token which I want to use for some further business logic of my application.

public static IEnumerable<IdentityResource> GetIdentityResources()
        {
            return new List<IdentityResource>
                {
                    new IdentityResources.OpenId(),
                    new IdentityResources.Profile(),
                    new IdentityResource("IS_token", new []{ "IS_token" } ),
                };
        }

I'm also adding this claim in IssuedClaims inside my IProfileService as below.

public class ProfileService : IProfileService
    {
        private readonly IUserClaimsPrincipalFactory<ApplicationUser> _claimsFactory;
        private readonly UserManager<ApplicationUser> _userManager;

        public ProfileService(UserManager<ApplicationUser> userManager, IUserClaimsPrincipalFactory<ApplicationUser> claimsFactory)
        {
            _userManager = userManager;
            _claimsFactory = claimsFactory;
        }

        public async Task GetProfileDataAsync(ProfileDataRequestContext context)
        {
            var sub = context.Subject.GetSubjectId();
            var user = await _userManager.FindByIdAsync(sub);
            var principal = await _claimsFactory.CreateAsync(user);

            var claims = principal.Claims.ToList();
            claims = claims.Where(claim => context.RequestedClaimTypes.Contains(claim.Type)).ToList();
            claims.Add(new Claim(JwtClaimTypes.GivenName, user.UserName));
            claims.Add(new Claim(IdentityServerConstants.StandardScopes.Email, user.Email));

            //Get user claims from AspNetUserClaims table
            var userClaims = await _userManager.GetClaimsAsync(user);
            claims.AddRange(userClaims);

            context.IssuedClaims = claims;
        }

        public async Task IsActiveAsync(IsActiveContext context)
        {
            var sub = context.Subject.GetSubjectId();
            var user = await _userManager.FindByIdAsync(sub);
            context.IsActive = user != null;
        }
    }

My MVC client is configured as below

               new Client
                    {
                        ClientId = "mvc",
                        ClientName = "MVC Client",
                        AllowedGrantTypes = GrantTypes.HybridAndClientCredentials,
                        RequireConsent = false,

                        ClientSecrets =
                        {
                            new Secret("secret".Sha256())
                        },

                        // where to redirect to after login
                        RedirectUris = { "http://localhost:5002/signin-oidc" },

                        // where to redirect to after logout
                        PostLogoutRedirectUris = { "http://localhost:5002/signout-callback-oidc" },

                        AllowedScopes = new List<string>
                        {
                            IdentityServerConstants.StandardScopes.OpenId,
                            IdentityServerConstants.StandardScopes.Profile,
                            "IS_token",
                            "api"
                        },

                        AllowOfflineAccess = true
                    },

In my MVC application, I have the following code in Startup.cs file

services.AddMvc();

    JwtSecurityTokenHandler.DefaultInboundClaimTypeMap.Clear();

    services.AddAuthentication(options =>
    {
        options.DefaultScheme = "Cookies";
        options.DefaultChallengeScheme = "oidc";
    })
    .AddCookie("Cookies")
    .AddOpenIdConnect("oidc", options =>
    {
        options.SignInScheme = "Cookies";
        options.Authority = "http://localhost:5000";
        options.RequireHttpsMetadata = false;

        options.ClientId = "mvc";
        options.ClientSecret = "secret";
        options.ResponseType = "code id_token";

        options.SaveTokens = true;
        options.GetClaimsFromUserInfoEndpoint = true;

        options.Scope.Add("api");
        options.Scope.Add("offline_access");
    });

When I authenticate user in identity server and get back to my secured link i got following claims but IS_token is missing from my users claims.

My secured page's cshtml

<dl>

    @foreach (var claim in User.Claims)

    {

        <dt>@claim.Type</dt>

        <dd>@claim.Value</dd>



    }

    <dt>access token</dt>
    <dd>@await ViewContext.HttpContext.GetTokenAsync("access_token")</dd>

    <dt>refresh token</dt>
    <dd>@await ViewContext.HttpContext.GetTokenAsync("refresh_token")</dd>

</dl> 

This is my secured page's screenshot

My secure page's output

As you can see in image IS_token is missing. How can i get IS_token claim???