** UPDATE **
Restored to factory settings - no go. 'Volume_1' is not displayed and attempting to create additional shares simply renames 'Volume_1' to the last share name entered.
Downgraded the firmware to 1.09; I can now see the following shares => paths:
Volume_1 => Volume_1
BT => Volume_1/BT
Looks like this may be a firmware issue with 1.10