Looks like it's picking up the USB and starting the boot process, but then suddenly stops with:

mount: proc mounted on /proc
mount: sysfs mounted on /sys.
mount: /sys/firmware/efi/efivars: unknown filesystem type 'efivarfs'.
	   dmesg(1) may have more information after failed mount system call.
mount: tmpfs mounted on /run.
mount: none mounted on /sys/kernel/debug.
waiting up to 30 seconds for device with label UNRAID to come online ...

umount: /: not mounted.
not found - press ENTER key to reboot...

I verified the USB drive is labeled properly:
 

sdw                                                 29.3G disk
└─sdw1                       UNRAID                 29.2G part

 

Edited January 27, 20251 yr by VACInc

Looks related to 

11 hours ago, VACInc said:

sdw1

This may still be a problem even with the update, please post the diagnostics from v6.12

Not sure if it's helpful, but I was having this same problem, system wouldn't boot, error screen mentioned:

mount: /sys/firmware/efi/efivars: unknown filesystem type 'efivarfs'.

Since I couldn't boot and Unraid runs bare-metal on my server, I decided to just get my flash drive and downgrade it in my own PC, but before I tried to just change the USB Port the flash drive was on and... it worked. V7.0.

Is this confirmed fixed in 7.0.1 becasue I have this issue with a Teramaster NAS. I have pulled the 6 HDDs (leaving just the 2 nvme drives) and still have the issue.
This is with a new install (waiting to lic until it proves functional)

v6 works without issues.