title: Mosquitto - No data in $SYS topics
body: <p>My setup has mosquitto 1.4.12 using TLS and user/pass authentication, it is working without issues under Ubuntu 14.04 for quite some time.</p>
  
  <p>Problem is that no data is being published to any <code>$SYS</code> broker status topics. I have reviewed the configuration and <code>sys_interval</code> is set to 10. Is anything else needed to have this working? </p>
  
  <p>I've tried many clients (mosquitto_sub, paho-mqtt, mqtt.fx), so it looks like a wrong mosquitto config, not a client issue.</p>
  
  <p>mosquitto.conf looks like this:</p>
  
  <pre><code>sys_interval 10
  
  max_queued_messages 10000
  max_inflight_messages 100
  max_connections -1
  
  connection_messages true
  log_dest stderr
  log_type error
  log_type warning
  log_type notice
  log_type information
  log_type all
  log_timestamp true
  
  password_file /etc/mosquitto/conf.d/jp.pw
  acl_file /etc/mosquitto/conf.d/acl.conf
  
  persistence true
  persistence_location /var/lib/mosquitto/
  persistence_file mosquitto.db
  persistent_client_expiration 1m
  autosave_interval 600
  retained_persistence true
  
  listener 8883
  tls_version tlsv1.2
  
  cafile /etc/mosquitto/ca_certificates/ca.crt
  certfile /etc/mosquitto/ca_certificates/cert.crt
  keyfile /etc/mosquitto/ca_certificates/cert.key
  require_certificate false
  allow_anonymous false
  </code></pre>
  
  <p>acl.conf has this, may be unnecessary:</p>
  
  <pre><code>user test
  topic #
  </code></pre>