OK I see; a minor comment on that - it was nice having the role permissions in the accordion (fewer clicks).

I have upgraded my site to 2.3.7.6 with no change to my problem. 

Nothing in system log. Will keep investigating when I have time - I need to solve this.

Hi Joe

I've cracked it.  The problem is caused by giving (only) the Administrator role edit permission on the page. Once you do this, then all the symptoms above emerge. Users in any other roles cannot edit features on the page even if they are given explicit permissions to do so. If you give their role edit permissions on the page, they can then edit the features.

Is it a bug? Probably not, because I've now read in detail the paragraph in the page editing section...

Administrators and Content Administrators can view or edit any content. Therefore Content Administrators role is not shown, and there is no need to ever check the Administrators role except for the special case where you would like to lock out Content Administrators so that only Administrators can view or edit the content. In that case you can check only the Administrators role and no other roles and Content Administrators will not be allowed. However to protect content instance(s) on the page you should set Administrators as the only role in the Feature Instance Settings as well, otherwise Content Administrators can still get to it from the Content Manager page

So it seems we had accidentally put the page into "protected" mode.

But although we had dug our own grave here, I do think this is quite confusing (borne out by the fact that even you couldn't think of any way of achieving the symptoms I was seeing ;-)

I wonder if instead of including the Administrators role in the normal checkbox list (which is pointless except for the above special case), there could be a separate controller for "Allow only Administrators to edit this page and its features" [chk] (with help text that this overrides explicit permissions on the features, except for Content Admin who can get at them...etc).

Or just "Protected page?" [chk]   (yada yada help text)

I feel this would be much easier to understand for bears of little brain like me.

Hi Jamie - I've bounced this around a few colleagues today (asp.net geeks and web devs) and we all agreed this should become a separate control to put a page into a special state of admin only / protected (etc), rather than including the admin role as a check box with special meaning.

So I think on reflection I'd still support my request for making this a separate override control as suggested in previous post.

I hope you can at least give this some thought, because this issue has clearly caused much confusion and wasted time for us and many others (admittedly because we were incapable of reading and understanding the help!).