I’m guessing others are going to experience this as well, so I’m posting it here. In the last version of the cart the text in the content editor was always black-on-white and then on the actual website the css took over and made it conform to the site design.
The site I am working on now has a dark background with white text on the live site. After upgrading to 2.2.1, the admin area is now showing white text (on a white bg) instead of black so it is really hard to use. The html editor shows black text, but the ‘preview’ editor shows white.
It appears that the preview mode of the editor is grabbing the site’s stylesheet (?) to make the text white, but unfortunately it is not recognizing the background color and so editing has become rather problematic, since my client has no desire to edit html source code.