It could be OneDrive is slow, or it could be a bug in how the app sees music on OneDrive.
What I'm wondering now is if you can use this to download your music to your phone over WIFI instead of plugging it in (i.e. a return to wireless syncing that we had back in WP7). I'm at work, so I can't test this myself, but what I want to do ultimately is put all my organized music in that OneDrive folder (I've got plenty of space, I think I only use 2% of my OneDrive space thanks to all of MS' free promotionals) and then set them to download onto my phone over WIFI.
It'd be a lot more convenient over having to plug my phone in and use the Windos Phone App for Desktop to sync.
The short answer is yes, you can do this. However it's currently a rather clunky and time-consuming process. I've been playing around with it since last night and have had mixed results:
After you have added all your music to your OneDrive folder, you have to open the XBM app on your phone - under settings you must enable "Connect to Streaming Music." If you do not enable this option, you will not see any of your OneDrive music. Next go to your list of all Songs - all your OneDrive music should be visible now under the "Streaming" filter. You can then select any songs (or select all) and click Download - they should download to your device.
NOTE - I do not know how this will jive with any existing subscription/streaming music you may already have. I do not subscribe to XBM and had no previous cloud-matched songs, or subscription content. So for me it was relatively simple in that my music collection is only what I have in OneDrive. I don't know if incorporating other cloud music would screw things up, as the current XBM app on WP does not let you filter between subscription streaming music or OneDrive streaming music - they are both just located under the Streaming filter.
Hiccups I've encountered:
- Songs will ONLY download while you are in the XBM app - if you navigate to any other app or the home screen, the downloads will pause. They will also pause if the screen locks. So if you're looking to download a big collection, be sure you set your lockscreen to never time out. Downloading a large collection for the first time (as I'm doing) will use a lot of your phone's resources - be prepared for intense heating, app crashes, etc.
- The system will create a new folder hierarchy that is different than how the Windows Phone app syncs your music, or how you would usually do it if you manually dragged and dropped music. The new structure you will see on your phone if using the File Manager app is: Music > Xbox Music > OneDrive Cache. Rather than the actual filenames you have on your music files, you will see a series of codes to represent each file. Also if you look under your phone's Storage Sense app, these music files will appear as unrecognized files in the Other storage section, not in Music.
- I'm unsure how the phone will handle playlists. For me this has been a big sore spot with XBM since it was introduced. Ideally I would like to use the XBM cloud playlist feature, where all my playlists automatically sync across devices. Currently playlists on my phone and in the XBM web app sync - however they do not sync up with the XBM for Windows 8.1 app on my PC. I spent about an hour chatting with XBM customer support yesterday and they had no idea what was going on, or whether this was supposed to be a feature or not.
- I'm getting a very different experience as far as metadata and album art when downloading my music from OneDrive. All my music is thoroughly tagged using MP3Tag, and all album art is embedded in each file. In the XBM app for Windows 8.1 (on my PC) everything displays correctly. It also displays correctly in Zune, iTunes, and Windows Media Player. So I know my metadata is correct - however when I view my music in XBM for Windows Phone 8.1 there are mistakes, i.e. wrong album art, albums being split, artist names being changed, etc. I also see these exact same issues in the XBM web app - again it looks like we are back to XBM overwriting or not correctly recognizing user-generated metadata.