In the hope it helps people in the future, I fitted one of these kits to my 2019 vRS Estate over the last couple of days but couldn’t get it to work - very simply, no response at all when putting the car into reverse.
I contacted Sinosmart via WhatsApp for help and they commented that there’s a manufacturing issue with the dashboard end of the long camera cable. Where it connects to the converter harness, the arrows don’t align with the keyway which means that it doesn’t mate up properly if you line up the arrows (like I did originally).
Hopefully the photo attached will show roughly how the arrows should look to align the keyway, but make sure the two halves are then pressed home to make the connection sound.