Letting subordinate users edit pages published by an Admin

We run a multisite network which we use for creating business sites. We (as admins) initially create pages and posts, copy in their data, then publish. Once we turn the site over to the users (revisor role as created by the Revisionary plugin) they are free to update and add new content as they see fit.

The issue lies in the revisors updating previously published content. They cannot add images using the Add Media button the the edit screen – they receive the “Cheatin ‘uh?” message. If the revisor were to create a new page, they could add images without issue.

I’m looking for ideas as to what could be causing this and if there are any known workarounds as we have been dealing with this since the release of 3.4. Currently, the workaround we offer is to upload media using the Media menu and manually inserting it into the page or post.