Localstack unable to locate a lambda function within any region other than us-east-1 when using AmazonLambdaClient

Using LocalStack pro 0.14.3, I created a simple Lambda function which takes in a string input and returns a string. I used the below to create a function in localstack.

awslocal lambda create-function `
--function-name "simple-lambda1" `
--zip-file fileb://C:\SimpleLambda\SimpleLambda\SimpleLambda1.zip `
--handler SimpleLambda::SimpleLambda.Function::FunctionHandler `
--runtime dotnetcore3.1 `
--role arn:aws:iam::000000000000:role/lambda-dotnet-ex

Here is my unit test.

[Test]
        public void Lambda_Function_Call_Succeeds()
        {
            var _lambdaClient = new AmazonLambdaClient(new BasicAWSCredentials("temp", "temp"), new AmazonLambdaConfig()
            {
                ServiceURL = "http://localhost:4566"
            });

            var input = "test";
           
            var lambdaInvokeRequest = new InvokeRequest
            {
                FunctionName = "simple-lambda1",
                InvocationType = InvocationType.RequestResponse,
                Payload = JsonConvert.SerializeObject(input),
            };

            var lambdaInvocationResponse = _lambdaClient.Invoke(lambdaInvokeRequest);

            var js = new JsonSerializer();
            var result = js.Deserialize<string>(lambdaInvocationResponse.Payload);
            Assert.AreEqual("WELCOME TEST", result);
        }

The above works fine but when I specify the region to be eu-west-1 when creating the function and then trying out the same unit test, I get the below exception which is correct.

Amazon.Lambda.Model.ResourceNotFoundException: 'Function not found: arn:aws:lambda:us-east-1:000000000000:function:simple-lambda1'

I tried adding the region to the lambdaclient.

[Test]
        public void Lambda_Function_Call_Succeeds()
        {
            var _lambdaClient = new AmazonLambdaClient(new BasicAWSCredentials("temp", "temp"), new AmazonLambdaConfig()
            {
                ServiceURL = "http://localhost:4566", RegionEndpoint = RegionEndpoint.EUWest1
            });

            var input = "test";
           
            var lambdaInvokeRequest = new InvokeRequest
            {
                FunctionName = "simple-lambda1",
                InvocationType = InvocationType.RequestResponse,
                Payload = JsonConvert.SerializeObject(input),
            };

            var lambdaInvocationResponse = _lambdaClient.Invoke(lambdaInvokeRequest);

            var js = new JsonSerializer();
            var result = js.Deserialize<string>(lambdaInvocationResponse.Payload);
            Assert.AreEqual("WELCOME TEST", result);
        }

But the above code gives me a Amazon.Lambda.AmazonLambdaException: 'The security token included in the request is invalid.' WebException: The remote server returned an error: (403) Forbidden. Is there anything obvious that I'm doing wrong ?

Here is my docker compose file

version: "3.8" 
services: 
   localstack: 
        image: localstack/localstack:latest
        container_name: localstack_test         
        privileged: true 
        ports: 
            - 53:53
            - 4510-4599:4510-4599            
            - 8000:8080
        environment: 
           - LOCALSTACK_API_KEY=XXX
           - SERVICES=s3,sqs,dynamodb,lambda,cloudformation,ssm,iam,cloudwatch,sts,kinesis,events,xray,ecr           
           - DATA_DIR=/tmp/localstack/data     
           - LEGACY_PERSISTENCE=false
           - EDGE_PORT=4566 
           - PORT_WEB_UI=8081 
           - START_WEB=1
           - DEBUG=1 
           - LAMBDA_EXECUTOR=local
           - HOSTNAME_EXTERNAL=localhost
           - LOCALSTACK_HOSTNAME=localhost
           - REQUIRE_PRO=0               
        volumes: 
           - c:/localstack:/tmp/localstack 
           - '/var/run/docker.sock:/var/run/docker.sock'  
        networks: 
            - localstack-ent 
networks: 
    localstack-ent: 
        external: false 
        driver: bridge