Not double spacing when compiled...

Everything works perfectly and as expected, except that when I compile and want to save a document as a novel manuscript it’s not double spacing the document. It’s set to double space in the compile settings. I don’t have maintain styles set for anything, I’ve checked all of that - does anyone know what might be wrong?

Unfortunately the OS X .doc and .docx exporters are notoriously buggy, and they wipe out double-spacing. Compile to .rtf instead of .doc or .docx (Word and other word processors open .rtf just as well) and you should be good.
All the best,
Keith