Edit Preview not working for membership group with 'edit only' permissions

I have a simple website in development. Have configured some pages to have a link containing {cp_edit_entry_url} tag exposed to logged in users who are part of a membership group with permission to edit the channel / entry content generating the page. The pages concerned are all available / visible to all users of the site.

The membership group has limited permissions - it can edit entries but not create new or delete entries.

The users with edit permissions can hit edit link and if they do they see the standard CP content editing page. Any edits they make and save are reflected in the content. If they try to open the page Preview they see an error page with message Error: you are not authorised to access this page.

If a user with super-admin rights edits same page, the Preview function works without problem.

Not sure what I’m doing wrong - I am guessing this is a permissions issue. Not sure what it is, and documentation on this feature seems rather poor, nor can I find similar question on stackexchange etc. so asking here, .

Any ideas / suggestions would be welcomed!