It looks like a duplicate of old issue https://github.com/localstack/localstack/issues/78
But now it's reproducible for me with the latest version of LocalStack. 
queue_url = req_data.get('QueueUrl')
        if queue_url:
            return queue_url[0]
        url = config.TEST_SQS_URL
        if headers.get('Host'):
            url = 'http%s://%s' % ('s' if config.USE_SSL else '', headers['Host'])
        queue_url = '%s%s' % (url, path.partition('?')[0])
        return queue_url
def get_external_port(headers, request_handler):
    host = headers.get('Host', '')
    if ':' in host:
        return int(host.split(':')[1])
    
    
    
    return request_handler.proxy.port
UPDATE_SQS = ProxyListenerSQS()