Group Subscription cannot change User Profile - reports email in use

With a group subscription the admin or group member goes in to change their user profile details (e.g. address) but when they hit update it reports

"This email has been used by a different user. Please enter a new email"

And the changes are not applied. I was pretty sure this worked when the site went live about eight months ago, has an update changed the settings?

Hello Graham

That's strange to me. Could you please submit a support ticket sending us:

- Super admin account of the site
- A group admin account
- Link to the manage group members page

We are going to check to see what's wrong and get it sorted

Tuan