I have been messing with the app myself for a few days now. I primarily listen to rap and metal. The rap artists I like I can find on Milk all day. The metal bands I like to listen to, not so much. I just started having an issue with it crashing also, even when it's in the background. I had to reinstall and apparently it doesn't sync with my Samsung account yet because I lost all my personalised stations I created.
Rap and metal? What a combo

I listen primarily to metal and it seems to do OK. Pantera, All That Remains, Devil Driver, Trivium....all those show and play. What bands you trying to listen too?
Fwiw, I had to sign in, exit app, and restart app to get it to sign in properly.