same here.
My setup is Z390 deignare, i9 9900k. Exactly same spot, stuck and displays Apple stop sign with a url at. the bottom support.apple.com/mac/startup.
anyone with a solution?
There must be something wronng with the ports config but i tried booting on usb2, but the usb stick is not even seen there, so i plugged it on usb3 port. Even though, don't think this is the problem.