Use a message for a topic in Confluent.Kafka when consumer run

I'm using Confluent.Kafka(1.4.4) in a .netCore project as a message broker. In the startup of the project I set only "bootstrapservers" to the specific servers which were in the appSetting.json file and I produce messages in an API when necessary with the code below in related class:

public async Task WriteMessage<T>(string topicName, T message)
    {
        using (var p = new ProducerBuilder<Null, string>(_producerConfig).Build())
        {
            try
            {
                var serializedMessage= JsonConvert.SerializeObject(message);
                var dr = await p.ProduceAsync(topicName, new Message<Null, string> { Value = serializedMessage });
                logger.LogInformation($"Delivered '{dr.Value}' to '{dr.TopicPartitionOffset}'");
            }
            catch (ProduceException<Null, string> e)
            {
                logger.LogInformation($"Delivery failed: {e.Error.Reason}");
            }
        }
    }

I have also added the following code In the consumer solution :

public async Task Run()
    {
        using (var consumerBuilder = new ConsumerBuilder<Ignore, string>(_consumerConfig).Build())
        {
            consumerBuilder.Subscribe(new List<string>() { "ActiveMemberCardForPanClubEvent", "CreatePanClubEvent", "RemovePanClubEvent"
            });

            CancellationTokenSource cts = new CancellationTokenSource();
            Console.CancelKeyPress += (_, e) =>
            {
                e.Cancel = true; // prevent the process from terminating.
                cts.Cancel();
            };

            try
            {
                while (true)
                {
                    try
                    {
                        var consumer = consumerBuilder.Consume(cts.Token);
                        if (consumer.Message != null)
                        {
                            using (LogContext.PushProperty("RequestId", Guid.NewGuid()))
                            {
                                //Do something
                                logger.LogInformation($"Consumed message '{consumer.Message.Value}' at: '{consumer.TopicPartitionOffset}'.");
                                await DoJob(consumer.Topic, consumer.Message.Value);
                                consumer.Topic.Remove(0, consumer.Topic.Length);
                            }

                        }
                        else
                        {
                            logger.LogInformation($"message is null for topic '{consumer.Topic}'and partition : '{consumer.TopicPartitionOffset}' .");
                            consumer.Topic.Remove(0, consumer.Topic.Length);
                        }
                    }
                    catch (ConsumeException e)
                    {

                        logger.LogInformation($"Error occurred: {e.Error.Reason}");
                    }
                }
            }
            catch (OperationCanceledException)
            {
                // Ensure the consumer leaves the group cleanly and final offsets are committed.
                consumerBuilder.Close();
            }
        }
    }

I produce a message and when the consumer project is run everything goes perfectly and the message is being read in the consumer solution. The problem is raised when the consumer project is not run and I queue a message in the API with the message producer in API. After running consumers there is not any valid message for that topic that it's message is being produced. I am familiar with and have experiences with message brokers and I know that by sending a message it will be on the bus until it is being used but I don't understand why it doesn't work with Kafka in this project.