Hello.
I found that after upgrading a VyOS rolling installation with "add system image" there is no "USB Console" option for this new version.
But if I do install this ISO with "install image" "USB Console" is present in GRUB options.
Screenshots explained:
- Fresh system
- After "add system image"
- After "install image" for an image which showed no "USB Console" after "add system image".
Also I've tested it for a few another VyOS rolling latest version and result is the same.