Pysine doesn't detect an audio output on the Raspberry Pi

[Penguinatron]

It's a Pi 3 B+ with the latest Raspberry Pi OS, with Python 3.7.3.

Here's the error that I get at the beginning of any script which uses pysine:
ERROR:pysine:No audio output is available. Mocking audio stream to simulate one.

The audio output is set to analog, and audio plays correctly from YouTube and VLC. The code itself works just fine on my laptop (macOS 10.14.6).

P.S. - This is the first thing I've ever done on GitHub- I hope I've followed all of the rules correctly, but if I haven't, feel free to point out my errors.