We brought it to the LBS and asked them to pull the rear hub apart and inspect. Great feedback on that possibility. It would make sense that it is loudest when climbing because all of the weight is transferred to the rear of the bike.
On the electric, I tested with and without the front hub on and the same with the PAS magnetic disk.
Drivetrain all parts replaced at this point except the front crank, LBS inspected and found no wear.
Fingers crossed on the rear wheel.