When a character entity reference like – is used, it seems to be corrupted when changing the text style via the Visual Editor, such as bolding/unbolding, italicizing/unitalicizing, and underlining/un-underlining. In the en dash case, bolding changes it to ☃☃. I first noticed this in English Wikipedia, but it happens at test2.wikipedia.org as well. I confirmed this on both MacOS and Windows, using both Chrome and Firefox browsers.