On my Samsung Galaxy S7 I have a Grayscale Option under Vision Accessibility (NOT the one under dev options!)
When I activate it over the UI it works as expected. But when I activate it over ADB Shell with command: "settings put system greyscale_mode 1" the toggle_switch gets activated as expected, but the greyscale effect itsself is not activated. Is there a command to push this new settings? Or what am I doing wrong?
Regards - Timo