I've submitted the issue. Though now I think the problem is primarily embedded-font related. And since then I've read up on some of the issues having to do with embedded fonts. This may simply be part of that larger problem.
Otherwise, this
issue made me realize just how persnickety ADE is about CSS errors. A single extra bracket seems to be able to cause ADE to ignore all CSS in a document, which is what I was experiencing. And since I'm doing a fair amount of CSS style-writing by hand, it seems likely that it wasn't perfectly clean to begin with.