Hello Michael,
Sorry to hear the debugging options didn't work - but great news that you resolved the issue. I've had a look into this and found the following...
So it looks like at some point Firefox has stopped using the NSPR options for debugging. From Firefox 52 you can now do this dynamically using about:networking, documentation available here: https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/HTTP_logging
Go to about:networking, then select Logging. Change the log file to the location you want and set the Log Modules to "timestamp,negotiateauth:5". Then hit the "Start Logging" button and in a new tab visit the site you want to debug. The log will only be written when you come back and hit the "Stop Logging" button. Closing Firefox will undo the changes you've made and you'll be back to the default logging options.
Thank you for your time.
Stuart
... View more