Beats input debugging logs not working

[jbeck (Jarryd Beck)]

I'm trying to see debug logs for the beats input to logstash. I have run:

curl -XPUT localhost:9600/_node/logging -d '{ "logger.logstash.inputs.beats": "TRACE" }'

which responded with

{"host":"ip-10-239-197-23","version":"5.3.0","http_address":"127.0.0.1:9600","id":"3ef960df-26f7-43b0-8faa-b72896899aa9","name":"i-08cc896d6e894bcf2","acknowledged":true}

I can also confirm that it is turned on:

curl localhost:9600/_node/logging?pretty
{
  "host" : "ip-10-239-197-23",
  "version" : "5.3.0",
  "http_address" : "127.0.0.1:9600",
  "id" : "3ef960df-26f7-43b0-8faa-b72896899aa9",
  "name" : "i-08cc896d6e894bcf2",
  "loggers" : {
    "logstash.agent" : "INFO",
    "logstash.api.service" : "INFO",
    "logstash.codecs.json" : "INFO",
    "logstash.codecs.plain" : "INFO",
    "logstash.filters.metrics" : "INFO",
    "logstash.inputs.beats" : "TRACE",

But there are no logs relating to the beats input in /var/log/logstash/logstash-json.log.

Is there something I am missing or is this broken?