I took a look at the solder joints - under a microscope - and can see a less than perfect solder. I did do a conductivity test using a multimeter so I didn’t really suspect the solder as being an issue. I’ll clean up the solder joints later today - also the new board should arrive today so I’ll check on that one too. In the meantime I did have some luck with a “Heart Rate Click GY-MAX30102 Sensor Optical Heart-Rate Monitor Module for Arduino” so that has helped me with my immediate demo needs.