It probably has to do with the indexing issues like we are having on Surface RT. I'm no comp genius so if I'm wrong about this hopefully someone will correct me. Basically, from what I understand, your computer can't index an external drive and know what's there to pull files. On RT we can't put our music on SD card and have device pull it in because it doesn't look for it. I'm thinking it may be the same problem with Skydrive. It doesn't "look" in external drive for it. I may be completely wrong and hopefully somebody with more knowledge on subject will confirm or extrapolate. There are some work around for the RT issue, if it is the same issue, that might work. I never could get it to work right on RT but some did.