VS1053 ESP32 Microphone or Line Input no data available (streams-vs1053-serial.ino)

[pbrownpb18]

I am using the example at the link below, and am not able to get data from line or microphone audio sources.
https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-vs1053/streams-vs1053-serial/streams-vs1053-serial.ino
I have turned on full Debug. Once the copying starts, I see

[D] AudioOutput.h : 152 - bool audio_tools::CsvOutput<T>::begin(int) [with T = short int]
[D] StreamCopy.h : 115 - copy 1024 bytes 
[D] VS1053Stream.h : 277 - arduino_vs1053::VS1053& audio_tools::VS1053Stream::getVS1053()
[I] VS1053Stream.h : 303 - available: 0
[D] StreamCopy.h : 267 - available: 0
[D] StreamCopy.h : 202 - no data 
[D] StreamCopy.h : 115 - copy 1024 bytes 
[D] VS1053Stream.h : 277 - arduino_vs1053::VS1053& audio_tools::VS1053Stream::getVS1053()
[I] VS1053Stream.h : 303 - available: 0
[D] StreamCopy.h : 267 - available: 0
[D] StreamCopy.h : 202 - no data 

and so on, forever. The full log is available if helpful. I'm using a generic VS1053 board and a standard ESP32 board, as shown in the attached.

I've followed through the code and compared it to other examples and can't find anything obvious.
Any help or hints would be appreciated. My next step would be to log all the register writes during setup.
Thanks