I am more than a little annoyed - that was a BIG selling feature. I have a Samsung phone, watch, and now 3 TV sets. This misinformation will cost them future sales to me and anyone I talk to about their products.
same problem for me too! It's so weird that the setting is there in normal tv mode. Though now I look , I'm it's called motion setting it seems to alter the brightness as well so may be working through the brightness sensor.
so annoying as clearly present as an option in the marketing!
In case this workaround helps anyone - Ive set an automation in smarthings to switch on the TV at sunrise. This switches on the TV and the art is back on the screen during the day and it still switches itself off at night ( cos I have the night mode on)