Q: Need suggestions for dealership to trouble shoot tire noise

A couple months ago a humming/shuddering sound started up at highway speeds and steadily got worse. Noise would increase while turning slightly. I had the front left CV axle replaced under warranty and at that time was told the noise was uneven tire wear not wheel bearings as I had suspected. I got 4 brand new tires while out of state at another Ford dealership. They also checked the bearings and found no problems. The tires are the exact same brand and size (Continentals 235/40R19 96V) that were on the car out of the factory. With the new tires the noise is still there. I brought it back to my dealership to check the bearings (3rd time a Ford certified mechanic has looked at them) and again they're saying no issues. They can't find the source of the noise and are trying to dismiss it as "tire noise". The noise is distracting and certainly sounds like something's wrong. I get NO steering wheel shake with it and it's heard at all speeds which points away from needing a balance (again).

My car has 43000 miles.
My car has an automatic transmission.