I had the exact same issue, and I found a fix.
Based on information from past forums of people struggling with this on old versions of WordPress, I installed the “Use Google Libraries” plugin, and then activated it (don’t forget to activate it, as it won’t activate automatically after installation).
It worked!
Apparently the plug-in “Allows your site to use common javascript libraries from Google’s AJAX Libraries CDN, rather than from WordPress’s own copies.” I’m not so sure about all that, but it fixed my issue with the Visual editor! (Giving me the feeling that my site is held together with my own sloppy coding/template adaptations, duct tape, shoe string and now plugins!)
