Debug log not working on nginx plus?

[oakh1]

I am running latest version of Nginx Plus (nginx version: nginx/1.25.1 (nginx-plus-r30)) and the debug log of this module does not work.

I have defined the error log such as:

error_log stderr debug;

I have also tried setting it to (without success):

error_log stderr debug_http;

And the nginx is started with "nginx-debug" instead of regular nginx (as you don't compile the nginx plus with ./configure)

What's weird is that I see the regular debug log from the nginx instance itself (lots of it - but not just the debug log from the SPNEGO module.

As an example output from the "regular debug log":

2023/09/28 22:38:09 [debug] 9#9: *7 free rr peer 2 0
2023/09/28 22:38:09 [debug] 9#9: *7 close http upstream connection: 13
2023/09/28 22:38:09 [debug] 9#9: *7 http upstream temp fd: -1
2023/09/28 22:38:09 [debug] 9#9: *7 http output filter "/?"
2023/09/28 22:38:09 [debug] 9#9: *7 http copy filter: "/?"

What's interesting is that I see the error logs from the SPNEGO module though. For example:

2023/09/28 22:26:42 [error] 9#9: *5 Kerberos error: Credentials failed, client: 10.x.x.x, server: internal.lab.domain, request: "GET / HTTP/1.1", host: "internal.lab.domain"

Am I missing something really obvious here. I've read the documentation several times but either I'm blind or somethings fishy?