itunes 12.2: Genius results can't be updated right now. An unknown error occurred (4001)

I have signed up to Apple music on my iPhone 6 and all is fine (apart from the early bugs that we are all aware of). When I switch on iCloud music library via Edit>Preferences>General it says it is "waiting for Apple to deliver your iCloud music library" but eventually it appears to timeout with the error below. I have 23,595 music files so the 25,000 match limit isn't the issue. Any ideas???