Hi, as you have the dealers looking at it already, all I can do is offer an example of a similar fault I had when working as a main dealer technician for a uk manufacturer.
I had an automatic (cvt) car in, it seemed to drive and change gears okay other than after braking.
The customer reported a abrupt jerk away when taking their foot off the brake pedal and on to the accelerator in traffic, that didn't seem to present when I drove the vehicle.
After some hunting and head scratching, I found that one of the flexi brake hoses had partially internally collapsed, it was allowing fluid under pressure into the caliper, however the slight internal collapse meant that the fluid pressure could not easily return from the caliper and this had the effect of holding the brake on that wheel and slowly releasing it as the pressure reduced.
I couldn't easily measure the pressure applied to the pedal, so I used a large piece of blu tak on the pedal, when I braked the blu tak was hardly deformed, after the customer had operated the pedal a few times in the car park, the blu tak was almost flat and adhered to the pedal rubber, the customer had a fairly hefty press on the pedal which amplified the fluid retention fault caused by the flexi hose.
Sorry I can not give you a specific answer remotely but I hope this gives you something to consider.