I found a workaround specifically for the AW2725Q:
Open the monitor's OSD menu.
Navigate to Game > Console Mode and set it to Legacy.
This forces the monitor to cap at 4K 120Hz (applies to HDMI only), freeing up bandwidth for the second display.
As long as the system detects the "Legacy mode" monitor first, you can successfully run both monitors simultaneously at 4K 120Hz!
Topic:
App & System Services
SubTopic:
Hardware