Show advance filter is not available in Portal case

Hello Fulgen, 

Basic functionality doesn't include the ability to apply filter conditions based on the connected objects  for the portal user directly in the section, therefore the advanced filter option is not available for such user there.

As a workaround you may use a dynamic folder and set the needed filter conditions for it. 

Also, we already have a query registered for our responsible R&D team to implement this functionality for portal users in the upcoming versions of the application. I will assign your case to this project in order to increase its priority.

Thank you!

Best regards,

Anastasiia