I am now writing this from a Live Manjaro OS. It seems that the issue was indeed USB related. While in the BIOS, I tried disabling my USB 3.0 controller entirely (legacy USB was already enabled) and moved the USB to one of the USB 2.0 headers on the back of the motherboard. To my surprise, the Live USB booted fine.
Since then, I've re-enabled USB 3.0, and as long as the USB stick is plugged into a USB 2.0 port on the back of the motherboard, the live USB boots.
I wanted to give the solution in case anyone else runs into this issue.