NGINX. No longer adding Header or Gziping

SYSTEM INFORMATION
OS type and version Debian Linux 12 - Linux 6.1.0-31-amd64 on x86_64
Webmin version 2.302

I was checking my system responsiveness using GTMetrix, and my performance goal went from 99% (when last checked) down to 81%.

Looking into this, I discovered that I was no longer:

1/ None of my add-header directives are being written into the HTML header section.
Which also means none of my expires are being written.

2/ Gzip is no longer working. Nothing is getting compressed.

I’ve spent the day trying to figure out what happened. None of the .conf files have been changed. It always passes the configuration test. I can stop and start NGinx with no problem.

Any help would be gratefully received.

Take Care - Nigel.