DIAGNOSIS The USB-C port on the PA278QV provides data and video (DisplayPort Alt Mode) but does NOT provide Power Delivery (PD) for charging connected devices. The downstream USB-A ports on the hub are only active when the monitor is connected to a computer via its upstream USB-B port.
FIX For charging: You must use your MacBook's original power adapter separately. The monitor's USB-C cable only carries video and data. For the USB hub: Connect the included square USB-B to USB-A cable from the monitor's 'USB Upstream' port to a USB port on your computer. Once this upstream connection is made, the two USB-A ports and the audio jack on the monitor become active, functioning as a hub.
IF THAT DIDN'T WORK Ensure you are using a fully functional USB-C cable that supports data and video. Try a different cable. On your Mac, check System Preferences > Displays to ensure the monitor is recognized. For the USB hub, try a different USB port on your computer for the upstream cable, and ensure the monitor is powered on.
HEADS UP This is a specification limit, not a fault. The PA278QV's USB-C port delivers up to 65W of power *to the monitor* from a compatible laptop charger, but it does *not* send power out to charge a laptop. Always check the upstream USB-B connection for hub functionality.