Odd, I'm running Manjaro too but the i3 community version using pulse and alsa. I have another computer I that has Manjaro KDE with pipewire, but that's playing the sound as normal as well. The version of miniaudio.h I'm using is from years ago at this point so I might just need to update it. It's definitely _trying_ to fall back to ALSA but I'll have to add more debug logging.
Thanks for checking it out, I'll see if I can do something about it.