I'm using ID CS6 on Mac OS X Lion. I am learning as I go--I used to work with PageMaker about 10 years ago, so it's not completely unfamiliar, but I know there is a lot I don't know yet.
On the project I've been working on, when I select "find Font" -> "Change all", sometimes the font changes as directed, but about 30-40% of the time I lose text instead. Sometimes it deletes just the italicized words, sometimes I lose everything in the document. I've tried deleting my ID preferences, and I've tried switching templates, but the problem keeps coming back.
From googling this problem, I see that there are other ways to switch fonts, and I hope to learn them, but the "Find Font" feature is supposed to work, and I really wish I knew how to make it work consistently without being afraid of losing text.