I'm also having the identical problem with external monitor connected via only HDMI. No problem with DisplayPort.
Screen does not wake up from sleeping when using refresh rate 240 Hz. It is fine with 60 Hz.
My graphics card is RTX 2070 Mobile
Using Ubuntu 20.04.3 LTS and Nvidia driver 470.86
I'm also having the identical problem with external monitor connected via only HDMI. No problem with DisplayPort.
Screen does not wake up from sleeping when using refresh rate 240 Hz. It is fine with 60 Hz.
My graphics card is RTX 2070 Mobile
Using Ubuntu 20.04.3 LTS and Nvidia driver 470.86