[dnanian]

There are hardware peculiarities with non-Oxford chipsets that show up in weird ways. The drives can become unbootable (even though the contents are bootable), can fail under load... all sorts of things can go wrong.

I don't think there's a fixable "glitch" as such. The fact that they're not even showing up in the Option-boot list means that they're either partitioned wrong (as "Master Boot Record") or that the drive just isn't responding properly.

This all assumes they're properly copied with "Backup - all files" and "Smart Update" or "erase, then copy".