hi, i've just run into the same issue, any luck since your last post?
No. No answers at all.
I think the portal filtering added to v11 does not affect the php engine. I think the documentation is referring to limiting the found sets to just a specific portal, but not to the portal filtering within that portal. Does that make sense?
If you want to create the portal filtering in php you need to create a relationship with multiple conditions that include whatever filter you need.
I was also trying to use setRelatedSetsFilters without luck. I could set via getRelatedSetsFilters and then use getRelatedSetsFilters to see the changes were set, but it doesn't seem to affect my results with getRelatedSet- maybe it's not intended for that.
I followed David's advice and setup relationships that do the filtering I was previously acheving through the portals. One good thing I just discovered is that the sorting set in the portal does change the sorting of results from getRelatedSet.
Another workaround that I used in my database is that I set the Record access for the privledge set that my PHP user uses to not allow access to items that would normally be filtered. I'm using PHP for a read-only version of the database. I have a field that's a flag if the record is ready to be viewed. In the Record data access section of the Privledge set, I set a custom privlege and limited access to the table when "Viewable = "Yes"". The result is that only viewable portal items are returned. This solution would only work if you never want to give PHP access to some records.
I had the same problem with v11, until I discovered that my permissions were too restrictive. One of my potals was sorted by a value list that the account I was using in PHP had no access to. (doh)
I didnt even have to use setRelatedSetsFilters().