there are two interesting things about this noise problem from the rear wheel.
(if it is the rear wheel)???
1. It was checked out by Porsche mechanics and no problem found. ……….
2. Comes and goes.
The E-brake idea is something I wasn't thinking of, good call.
I would think a half decent mechanic would have checked it though.
It is something the OP can check in the way described and perhaps find the problem or check it off the diagnosis list.
keep us posted
