grpc-dotnet: Interceptor not being called

Hi,

I am trying to create a grpc interceptor that will add a bearer token to the request header on every call if it is available. This is in blazor wasm with pre-rendering and my grpc package versions are 2.37.0

My interceptor code

public class GrpcAuthInterceptor : Interceptor
    {
        private readonly string _apiUrl;
        private readonly string[] _scopes = new[] { "somescope" };
        private readonly AuthenticationStateProvider _authenticationStateProvider;

        public GrpcAuthInterceptor(string apiUrl, AuthenticationStateProvider authenticationStateProvider)
        {
            _apiUrl = apiUrl;
            _authenticationStateProvider = authenticationStateProvider;
        }

        public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(
            ClientInterceptorContext<TRequest, TResponse> context,
            AsyncClientStreamingCallContinuation<TRequest, TResponse> continuation)
        {
            Console.WriteLine("In add async client streaming call");
            AddCallerMetadata(ref context);
            
            return continuation(context);
        }

        private void AddCallerMetadata<TRequest, TResponse>(ref ClientInterceptorContext<TRequest, TResponse> context)
            where TRequest : class
            where TResponse : class
        {
            Console.WriteLine("In add caller metadata");
            var headers = context.Options.Headers;
            
            var authState = _authenticationStateProvider.GetAuthenticationStateAsync().GetAwaiter().GetResult();
            var user = authState.User;
            Console.WriteLine("grabbing a user");
            var token = user.Claims.FirstOrDefault(a => a.Type == "access_token")?.Value;
            Console.WriteLine($"{user.Claims.Select(_ => _.Value)}");
            // Call doesn't have a headers collection to add to.
            // Need to create a new context with headers for the call.
            if (headers == null)
            {
                headers = new Metadata();
                var options = context.Options.WithHeaders(headers);
                context = new ClientInterceptorContext<TRequest, TResponse>(context.Method, context.Host, options);
            }

            // Add caller metadata to call headers
            headers.Add("grpc-internal-encoding-request", "gzip");

            Console.WriteLine("adding token");
            headers.Add("Authorization", $"Bearer {token}");
        }
    }

I add the interceptor to DI with this line of code

services.AddSingleton(new GrpcAuthInterceptor(apiUrl, services.BuildServiceProvider().GetService<AuthenticationStateProvider>()));

I add the interceptor to the grpc client like

serviceCollection
                .AddGrpcClient<SomeClient.Client>("clientname", options =>
                {
                    options.Address = new Uri(apiUrl);
                })
                .AddInterceptor<GrpcAuthInterceptor>()
                .ConfigureChannel(options =>
                {
                    options.ServiceConfig = new ServiceConfig { MethodConfigs = { defaultMethodConfig } };
                })
                .ConfigurePrimaryHttpMessageHandler(() =>
                {
                    var handler = new GrpcWebHandler(GrpcWebMode.GrpcWeb, new HttpClientHandler());
                    return handler;
                });

I can see the constructor of the interceptor being called but no other methods are called. Any help is appreciated thank you!