Under AutoCorrect options, it clearly shows: Automatic bold, /italic/, -strikeout- and underline
When I apply Autocorrect to an older document, it completely ignores all the words inside /slashes/. It makes asterisks bold and underscores into underlined text, but absolutely will not make italics. Only if I type new text, and add slashes, will it turn them into italics. It will not touch the preexisting text.