Metadata server error trying to configure CloudBoost appliance

Trying to add a CloudBoost 2.2.2 (or 2.2.3 - tried on both) running on Azure.

After getting over a JCloud error, which was due to using the Key rather than connection string for the storage blob, I'm faced with a new error:

Could not apply initial configuration. Reason: Share creation failed. Reason: Error while deploying Metadata server.

Looking at the logs on the box I don't see anything particularly helpful for the reason for the failure this time though...  There's various errors, ending with:

2018-04-12T10:01:46.669+00:00 [WARN ]        config_DJ.1868  , command_info.rb:318                , Deleting failed command 0c66a025-3e38-11e8-9d57-02420a4e0108: Command progress: 100 Reason for failure: Could not apply initial configuration. Reason: Share creation failed. Reason: Error while deploying Metadata server.

2018-04-12T10:01:47.790+00:00 [INFO ]        config_DJ.1868  , event.rb:49                        , Event log: [:INITIAL_CONFIGURATION_FAIL

, "", {}]

2018-04-12T10:01:50.270+00:00 [INFO ]      cloud_agent.2058  , config_info.rb:389                 , Failed to apply configuration: Reason Could not apply initial configuration. Reason: Share creation failed. Reason: Error while deploying Metadata server.

Any suggestions welcome!