Invited cloud user gets no registered devices

RN10400 OS 6.1.4 2x3TB WD Red

I have set up the above machine successfully using the readycloud discovery process and have no problem accessing it using the admin user via readycloud or any of the relevant iOS apps.

My problem is this: I invited another user to access my NAS using the Manage tab of readycloud. That user responded to the email and set up a readycloud account, which is now visible on the Manage tab of readycloud, if one is logged in as the admin user. However when the invited user logs into readycloud, no NAS is visible and the text "Currently you have no registered or shared devices". How do I get my NAS to show up for that user? The invited user has all the services (readycloud, remote, readydrop) appear after the user's name under the Account tab, Cloud Users section, exactly as they do for the admin user. However, only the admin user can see the NAS when logged in through the cloud.

Also, while the admin user can log in to the NAS directly, using its IP address in a browser, the invited user cannot log in that way at all!

Please can someone tell me what I am doing wrong, or not doing at all?