I was running 275.xx and upgraded to 280.xx drivers. I have trees set to Low and with the upgrade - no trees (I didn't try higher settings!) Rolled driver back and trees are back..
Think I will stick with 275.xx driver as I am not sure what else the 280.xx upgrade will affect.
I only mention this because Luthier asked for driver versions to be included in any bug reports and I may well have confused this as a beta bug.