First bad experience in the S8

[Delboy]

The auto lock is speed dependent and engages once the set speed is reached.

You ought to do some digging into the boot locking with keys inside as it shouldn't do it.

My cars the same year as yours and when I left the keys in the boot it opened straight away and I tried numerous times to close the boot for it to only open again until I realised that the keys were in the boot.

I also today left the keys in my jacket on the passenger seat and tried to lock it on the button on the door handle and it refused to lock.

Try locking one set of keys in various places in the car while you have the other set handy and then swap keys and do the same again to see if both keys behave the same.

Could be a weak key battery or possible a defective antenna in the boot