OK, another experiment.
Purchased brand new receiver from Audi, disemboweled center console, installed the new receiver in OEM location with OEM bracket, fixed with OEM screws and it didn't pass the 2:59 test!
It all happened in garage, not exactly on the same spot where we tested Adrian's car.
I think I'm going to bury that receiver in OEM location and will snake wires to boot under parcel shelf where another receiver did work.
Update: and then it passed test from 3rd attempt!
I'm now taking old receiver and will test it on the same location... To be continued...