Possibly - it was a USB stick that I had just sitting in a little pile of them...
This is not a major issue and I will dig out another USB stick to continue my review of the 6.12.0 RC releases - although I'm pretty happy with the new features up to now with all my testing scenarios being successful. My focus has been on the new native ZFS support - I aim to move non-media files to ZFS but retain the existing "unRAID Arrary" for my media files.