Diagnosis
This is a common handshake failure between the monitor's power-saving state and the PC's graphics driver.
How to Fix It
First, adjust the monitor's deep sleep setting. In the OSD, navigate to 'System' > 'Power Savings'. Set it to 'Off'. This prevents the monitor from entering a ultra-low-power state that some PCs cannot wake. In Windows, open Power Options. Edit your plan settings. Under 'PCI Express' > 'Link State Power Management', set it to 'Off'. This keeps the GPU's output active during sleep.
If That Didn't Work
The issue may be specific to your graphics driver's handling of DisplayPort. In your GPU control panel, look for an option like 'DisplayPort 1.2' (or '1.4') and ensure it is enabled. Alternatively, try using an HDMI 2.0 cable as a test, as its wake-from-sleep behavior can differ.
Heads Up
Some motherboard BIOS/UEFI settings can affect USB-powered wake signals if you are using a USB upstream cable for the monitor's hub. If not using the hub features, disconnect the USB-B upstream cable from the monitor, as it is not required for video and can complicate power states.