Good Morning

I need some advice and help.

At the last major service of my GU patrol the dealership had to repack the front wheel hubs.
Since then there has been an infrequent rattling noise in the wheel hubs.

The best way to describe the noise it is like when as a kid on your bike you used to put a footy card in the wheel spokes to make it sound like a bit of engine noise, only louder.

I have had it back to the dealership but they cannot find any problem, yet on occasion the noise persists.

As I say it is infrequent, heavy braking seems to trigger the noise and if I drive in reverse and hit the brakes it stops.

The front hubs are not engaged and are in the fully unlocked position, I have had the wheels off and there is no obvious problem to me.

So my question would be has anyone else encountered this problem, what caused it and how was it fixed?

Thank you all in advance, I hope you can help.