Hi Esmi,
I have tried deactivating ALL plugins, and resetting the Plugins folder to no avail. I also tried switching the theme over to the Twenty Eleven theme and that didn’t work either.
I haven’t tried uploading wp-admin and wp-includes again just yet, as we have 58 websites running from this trunk of WordPress.
I’ll speak with some colleagues since I’m new in my current role and wouldn’t want to do such a big edit on a whim.
Do you have any other suggestions I could try?
Database settings? Access control tweaks?
The Author dropdown appears fine for Admin users, but Editors don’t have the dropdown list inside the panel.
Here is what the Editor sees:
https://imageshack.us/photo/my-images/39/authorpanel.png/