Whenever I put my Macbook Pro running High Sierra to sleep my Asus PB277Q keeps waking up displaying a blue screen saying 'HDMI no signal' every few seconds, forever. Some other times it sleeps normally, and I can't tell what is causing the behavior.
From what I can tell the Mac itself is asleep. It makes no sound, Bluetooth is off, Wake for network access is off, sharing (internet for example) is off, removing USB devices changes nothing. The screen is connected to a Displayport to HDMI/DVI/VGA adapter, which in turn is connected to the screen over an HDMI cable.
Any ideas what else I can try?