I know they connected Smart Previews to a lot, but I don't believe draft mode was one of them. Happy to be wrong as my memory of it now is sketchy. Your experience seems to verify that. If you can export, why not reimport with the same name and build the sheet from that.
If you're looking for a proofing system, there's now one as part of Lightroom sync on your lightroom.adobe.com account.
Sean McCormack. Author. Magazine Writer. Official Fuji X-Photographer.