Volume drops when I adjust volume while playing a song

[Giyand]

Hi,
I'm using Spotify on HTC one m9 and ever some I upgraded to premium account I've had problems with the volume. When I change the volume up or down while playing a song it suddenly drops to a whisper and won't go up unless I skip part of the track with the progress bar.

Anyone had this problem? Any help would be appreciated.

Thanks