I thinke URE has caused a bug in my site. Editors can only see their own media in the edit post view. This is not default wp behaviour, and the only issues I can find by googling, is some related to URE. Now, I have unistalled the pro and free plugin, but the problem remains.
Are there still items from URE left behind when uninstalling?
Even deactivation of URE removes all additional restrictions set for roles and users. But the changes you made to roles (grant/revoke capabilities) are permanent and does not depend from URE presence at your site.
As restrictions for media library items are still in action after URE deletion – the source of a problem is in some other plugin.