I've had this happen to me before when swapping out different boot sticks - and it may not pertain to your hardware.
One one of my boxes, (a small cheap hockey-puck sized mini-pc), when I change boot sticks, it seems to need to be powered down, *and the power physically disconnected* and then reconnected with the stick I want to boot from before applying power. A simple power-off is not sufficient - I need to physically pull the power from the back of the unit and plug back in with the new boot stick already in place.
Seems like the system is taking an inventory of what is attached to the usb ports, and then quickly powers off internally waiting for you to manually power up. I can see an led glow for a few seconds and then it all goes dark.
Then it is no longer confused leaving me at a blank screen.
I'm not a big hardware guy, but I was tearing my hair out when I discovered this.
Could just be my specific hardware, but thought I'd throw that out.
Either that, or did you upgrade to 11.1 and possibly need the intel_iommu=off kernel cheatcode?