iPhone 5 (iOS 10.2.1), and I've been uploading songs directly from the mobile Garageband app for years. I also have a Pro Unlimited account, so I can't be 'out of space'. Yet for the last few weeks, I have got the message 'Can't upload to Soundcloud. Please check Account Details'. (I did, many times, they're fine). Not sure if this is a Soundcloud problem or a Garageband problem, but I've searched on the internet and don't seem to be the only one this is happening to.