iTunes library to Apple Music doesn't work

I subscribed to Apple Music hoping I could also upload my library (max. 100.000 songs) to iCloud. However, the uploading seems to crash all the time. It always comes up w/ unknown error (4010) saying something about Genius. How can I verify when and whether my songs have been uploaded and what can I do about this? Goes without saying that this is not something I expected. I'm running latest and greatest versions of Apple software on my iMac.