Solved
I was trying to debug USART2 code on a Nucleo-G0B1RE development board. Unfortunately the ST-LINK was on the same pins. I assumed that I couldn't use the STM32CubeIDE debug while the pins were in USART2 mode ... but I tried it and it worked. How?
This is not a priority question. I'm just curious as to how USART2 and debugging can operate at the same time but I'm happy that it does.
