ReadayNAS Ultra 2 can't see USB drive after update

[shawian]

I've just updated RAIDiator from 4.2.15 to 4.2.16 to 4.2.31.

The USB drive that was working as the backup drive on 4.2.15 can no longer be seen by 4.2.31. I've checked the USB drive by plugging it into the PC and it works fine - just cannot be seen by the ReadyNAS.

Suggestions?

[shawian]

No idea why, but after a number of reboots it has now become recognised.