I recently upgraded the Splunk Palo Alto Add-on from 3.8.0 to 6.0.2 on our ES search head. Since that change, the category is no longer being extracted properly and it is affecting the web data model which shows all traffic in the HTTP Category Analysis as "unknown".
This is an issue in the Add-on 6.0.2. According to the folks at PAN, it will be fixed in 6.0.3. The current workaround solution is by modifying the following file:
$SPLUNK_HOME/etc/apps/Splunk_TA_paloalto/default/props.conf
In that file, find the line that reads:
EVAL-category = threat_category
I believe it is line 76. Change the line to this:
EVAL-category = if(log_subtype=="url" OR log_subtype=="file", raw_category, threat_category)
Then restart Splunk to put the change into effect.