Windows can give an individual app its own volume and output device, separate from the system sounds you hear.
Why this happens
Hearing a notification proves that one Windows audio path works; it does not establish that every application is using that path. The player may be muted in the volume mixer, routed to a monitor or headset, or using its own low volume setting. This is especially easy to miss after connecting a display, docking station or Bluetooth device. The system speaker icon can look normal while the application you want to hear is using something else.
Keep the player running while you inspect the app entry in Windows Volume mixer. Compare its selected output and volume with the device you actually intend to use. Then check the player’s own mute and volume controls. Microsoft documents this app-specific troubleshooting route, which is more focused than reinstalling the streaming application as the first step. If the player is absent from the mixer, make sure it is attempting playback before drawing conclusions. Keep any driver or service investigation separate from this simpler routing comparison.
A useful way to work through it
Play a source and inspect that application’s Volume mixer entry.
Choose the intended speaker/headphone output and remove any app-specific mute.
Compare the player’s own volume control before changing drivers or reinstalling.