Configuring GraphQL.Server.Authorization and IdentityServer

Question

I'm trying to configure GraphQL-dotnet authentication with IdentityServer 4, but failing to get the token validation working. In UI-playground, I'm using the Chrome ModHeader extension to add the auth header, but it seems like api not registering the token - it fails with "You are not authorized to run this query. The current user must be authenticated.". Is there something I'm missing? Thank you in advance.

services
    .AddHttpContextAccessor()
    .AddTransient<GraphQL.Validation.IValidationRule, GraphQL.Server.Authorization.AspNetCore.AuthorizationValidationRule>()
    .AddAuthorizationCore(_ => {
        _.AddPolicy(Policies.Authorized, p => p.RequireAuthenticatedUser());
    })
    .AddGraphQL(_ => {
        _.SetFieldMiddleware = true;
        _.EnableMetrics = true;
        _.ExposeExceptions = !_hostEnvironment.IsProduction();
    })
    .AddGraphTypes(ServiceLifetime.Scoped)
    .AddUserContextBuilder(httpContext => httpContext.User);

services           
    .AddAuthentication(_ => {
        _.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        _.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        _.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
    })
    .AddIdentityServerAuthentication(options => {
        options.Authority = "http://localhost:5102";
        options.SupportedTokens = SupportedTokens.Jwt;
        options.RequireHttpsMetadata = false; // Note: Set to true in production
        options.ApiName = "api1"; // Audience
    });