I had this exact same problem yesterday on a clean install on a clean OS. Here’s how I fixed it. Not sure if this will work for you.
When I first went into System -> System Settings, "Enable Rich Text Editor" was set to "yes" but "Editor to use" was empty and had no options available.
1. I went into my /core/cache/ directory and removed all the files in here (not sure if this was necessary)
2. I then downloaded
http://www.mckinneymedia.com/core/packages/tinymce-4.1.2-pl.transport.zip as per a previous post and placed it into the /core/packages/ folder. I did not unzip the file.
3. System -> Package Management -> Add New Package -> Search Locally for Packages -> Next -> Yes
4. I then clicked ’Install’ for TinyMCE
5. I went back into System -> System Settings -> Double clicked the empty "Value" field for "Editor to use" and selected TinyMCE
It then started working for me from there.
Hope this helps.
