I've got a problem with this plugin. Installation is ok and I can select multiple authors to posts.
The users I select have the author role but only the first one in the author list can edit the post, the other ones don't even see it in the dashboard.
If I change the order of authors, then the new author on the top of the list can edit the post and only him.
In the matter of fact, I also use the Press Permit Core plugin to manage groups with reading access, I wondered if it can be a conflict between these two plugins, despite of the fact that deactivating PPC doesn't help to make co-authors plus work.
Thanks for your help.