Diagnosis
This is a failed wake-up signal handshake, commonly due to the computer's power management settings or a deep sleep state on the monitor.
How to Fix It
First, disable the monitor's deep sleep. In the OnScreen Control menu, go to General > Power LED and set it to On. If using a desktop, check the PC's Power Options. Go to Edit Plan Settings > Change advanced power settings. Under PCI Express, set Link State Power Management to Off.
If That Didn't Work
The issue is often specific to the input cable. For DisplayPort, ensure the cable is DP 1.4 certified. Try a different cable. For USB-C, the issue is frequent. Switch to using an HDMI cable for the video connection while using USB-C only for peripheral passthrough.
Heads Up
If the monitor's power LED is off (not blinking), it is in a mechanical off state. This happens if it loses AC power or is unplugged while the computer is off. You must press the button to restore power.