My understanding is that the platform has been pitched primarily as a "proof of concept" type thing to artists and labels with assurances that if enough people subscribe/stream the service and your music you can get paid out. My guess is that the forecasts and hopes aren't stacking up in payouts to the labels/artists quite how they hoped and the result is frustrating these individuals.

I'm sure there's a lot more at play here but this is what I've understood from the research I've done.