As far as moving the UART over to a different pin and getting better results, I'm wondering if it's related to an issue I was having where the console was taking over to the USART1 pins on the Puck when I disconnected from the IDE. Basically the same as this troubleshooting post:
Except instead of calling USB.setConsole(), for me the fix was to call:
I did this both on the init event, and at the top of my code, and it addressed the issues I was having where it looked like console activity was appearing on my serial connection when I connected and disconnected from bluetooth. This allowed me to interact with a UART device on the tx,rx lines...
Gordon or others, please correct me if I'm wrong here, but if this is correct, it might be worth it to add bluetooth related info to that troubleshooting page.