There’s lots of wiggly parts to check: AudioSources by default have listener effects enabled, which attenuates based on distance to AudioListener, etc.
Start from the audio file, select it an enable auto preview so you can hear it at full power in the editor, then work on into your game, perhaps side-stepping into a blank scene with a source and listener colocated.
And then if you use an AudioMixer there is an unbounded additional number of things to check.
I forgot to mention that it’s a 2D game and that the audio source is set to 2D. I still see an “Attenuation” option under the channel, and when I move the listener or object, the volume doesn’t change. I even tried placing the listener on the audio source object.