From what I see, you are correct. The files are filled with empty lines. This would mean there is a problem with your logging rules on Web Gateway, or perhaps it was deleted all together.
Policy > Rule Sets > Log Handler (bottom-left) > Expand to your Access Log rule set
Your problem is located somewhere in here. Click "Show Details" in the menu bar and you should see all the log fields on the right like my screenshot below.
Thank you very much Sroering,
You were right!
The rule was on "Set User Defined event Message", that's wy the files was empty.
Can you telle me the field to add int the log rule to see the AD group name in the quick view reports?