Hi all, recording this as a current problem in my MY23 Avant TDI40 Quattro.

Currently become an issue when reversing at low speeds car has covered 19k miles.

Non-obvious symptoms other than someone pointing this out to me in the car park. I can’t hear it in the cabin but it’s coming from the rear of the car not the front. It’s replicated by going forward and selecting reverse and throttle. 

sound is a distinct crunch/grinding sound only at low speed after selecting reverse.

further input after taking it in for diagnosis at main dealer.

Definitely recommend getting it to a main dealer. 

Could it be an issue with the synchromesh, linkage or an issue with the quattro system. 

Just to update

In true fashion, I had it booked in just before Christmas and it stopped doing its thing right before booking in.

it was up on the ramp and it was looked at but didn’t seem to be making any noises at all.

it could have been stone in the brake disc/heat shield. It could of been the electronic hand brake not fully disengaging.

they lubriated the handbrake cable mechanisms and said to monitor.

i now have another issue, but that is another thread… 

Thanks for the update, shame they couldn't find any issue. Sorry to hear you have a new issue.