If you're landing with air in the UAT then it sounds like it's doing it's job and trapping the air that's coming from upstream. Can you show another picture of your fuel filter? some of them have the direction arrow facing the wrong way and that could be back siphoning air.
If you're interested in peace of mind maybe worth checking our Intairco's new iTrap - it has a pressure sensor inside that triggers when it detects an air pocket - I'm putting one in my Rebel now..
On the left in this picture, the sensor is at the top and you can see the signal lead exiting to the left
