ReadyNAS 214 - Why is new Volume not appearing on my network?

Firmware 6.10.10. Check for updates, no new updates available
ReadyNAS 214.

I have added a new disk and created a new JBOD volume, but when I connect to the ReadyNAS through my network, I can't see this new volume. Any thoughts on how to address this?

Volumes are, in order of head position

DISKY2 - this is a 6TB
DISKY3B - this is a 10TB, and this is the one that's causing the challenges
DISKY3 - this is a 10TB, same type as 3B
DISKY4 - this is a 20TB

All four volumes have green lights on the 'volumes' tab.
All four volumes appear on the 'overview' tab.

All four volumes have show Volume State: NEW and Disk State: Online.

When I connect to this volume though the network (checked with multiple devices and OS), I see DISKY2, DISKY3 and DISKY4 but DISKY3B is not showing.

I have formatted DISKY3B and this has been several days, so it has been plenty of time to do any background processes that may have been running despite the disk showing online.

I have rebooted both the ReadyNAS device and my router a couple of times since.

Thanks in advance for any insight you may have