I'm having a similar issue, but both "Visual" and "Text" appear to be blank... however, the issue is that the text is set to white on a white background. When inspecting, I see the following:
(editor.min.css)
.js .tmce-active .wp-editor-area {
color: #fff
}
I suppose I can update this css myself, but I'm curious if this is caused by MetaBox, WordPress, or some other plugin?