Problem with Spotify

[Android Central Question]

I got problem with spotify. Controls on my headphones are not working when phone is locked or simply when spotify is inactive for more than 30 seconds (or so..). I think it should be problem of Android 9, because I had no problem before.. I could easily start to listening to music from my headphones when phone was locked.
When spotify is active, It's working even if the phone is locked..
Any idea please?