I found the fix. In the Access Lists for the user group, in Allowed excludefields -> Page Content you need to check Startingpoint (pages).
> Since upgrading to v7.6 a problem has appeared with the form for editing the menu/sitemap CE. Specifically the text box headed "Selected Pages" appears for admin users but not for others.
> I have looked through the access lists for users and groups but I cannot see which field would cause this effect.
> Can anyone suggest the solution?