Ubuntu 2304 beta blank screen not configurable

[mahesh]

I am using Ubuntu 23.04 beta on a Lenovo Legion 5 laptop with Gnome, X11, nVIDIA GeForce RTX 2060, Intel core i7.
In gnome settings under Power and then Power Saving Options there is Screen Blank, set to never.
But after less than a minute in idle, my screen is blank.
It seems these settings are not taken into account.
Is there another way?