I experience the same problem last year at Redflag. factory pick up in the tank wouldn't allow enough flow for the new G2 210g fuel flow. Never notice a problem on the first 210g I had in it.
My UAT would show up 1/2 full after a flame out at the end of a flight. I replaced it with the larger GBR filter type from Dream works there and also made sure the vent had no crimps. The old one had very slight crimps from bending so it could have also contributed.
I did a static test on the main single tank flow out of the plane and after the changes it increase over 25%, problem solved.
best of luck and hope you find it.