For me the following worked fine:
I installed the WordPress Helpers plugin.
In the “Writing” tab I changed “Editor” to “Only show Text editor” and “Set Default Editor” to “HTML” and pressed “Save Changes”.
Immedately after that I changed “Editor” to “Show Visual and Text editors” and “Set Default Editor” to “Visual” and pressed “Save Changes” again.
Now the visual editor is just doing fine again.
