Web filtering showing blank pages after FortiOS upgrade

[ams_sec]

Hello,

We are having problems with web filtering rules after we have upgraded to v5.2.1 build 0618. After the upgrade users are experiencing blank pages when browsing. URL's where this is happening are totally random but are showing up in the logs as accepted traffic. When we remove the web filtering policy there are no issues.

I have created a ticket with support, but they are not being very helpful. I was wondering if anyone else has experienced this and if anyone knows what can cause this behavior?