I had problems with additional arguments yesterday on one pfsense, too.
I just added the arguments and then "Force Update Now". This did not create a log.
Then I added the arguments, first clicked "Save" and then after using "Force Update Now" it worked.
Tried with "TODAY" and with "MONTH" and all is ok.
What marcelloc mentions is absolutly important:
As far as I understand it, SARG only analyzes the access.log file which is active. The old - rotated ones - will not be analyzed.
So if you rotate daily or in shorter times then you cannot get a report back for longer than one day.
If the access.log of squid contains 100 days in the past and then you do reports with the custom arguments then your results can be 1 months, 1 week, yesterday or today.
But if your access log of squid only contains 3 days it is not possible to create a log of the last week/month.
And marcelloc mentioned this, too:
If squid log rotation is enabled on squid GUI then squid will roatete logs every mindnight - this will result in the fact that SARG can only analyze the actual day.
So best ist to enable logging on squid GUI (neccessary) and leave the field "log rotations" empty so squid will not rotate the access.log.
Then create a shedule on SARG which creates an report and rotates the log. It dempends on you how many days a log should contain.
I for myself have two SARG shedules:
One which runs evey hour (1h) with no rotation and then one shedule which runs every day (1d) and does the log rotation.