Can't get debug logging options to work

I am trying to resolve a problem with Matomo so that it captures the correct visitor IP using proxy_client_headers[] = HTTP_X_FORWARDED_FOR.

This is not working so i am attempting to troubleshoot by enabling tracker logging and general logging, but I can’t get either of them to work.

I have attempted to enable debug tracker logging, by adding the following to config.ini.php

[Tracker]

debug = 1

I understand that enabling the tracker debug should show debug output in the HTTP response(?). However this is not working for me; all I see in the response is:

HTTP/1.1 200 OK

Date: Tue, 25 Jun 2019 11:10:04 GMT

Server: Apache

X-Powered-By: PHP/7.1.29

X-Frame-Options: SAMEORIGIN

Vary: Cookie

Content-Length: 0

Keep-Alive: timeout=5, max=98

Connection: Keep-Alive

Content-Type: text/plain;charset=UTF-8

Note that the request does appear in the Visitor log correctly.

I have also attempted to enable logging by adding the section below to config.ini.php - using both file and database options, unquoted and double quoted.

[log]

log_writers[] = file

log_level = "DEBUG"

This also does not seem to result in any log messages written to tmp\logs. I have also tried the ‘screen’ option, but nothing appears in the log viewer within the UI.