Resolved! HAL_UART_Transmit() works; HAL_UART_Transmit_IT() does nothing and breaks printf
I've got the NUCLEO-G491RE board and have it connected to my PC over the only USB port which is of course also used for the debugger. Both printf() and HAL_UART_Transmit() work to send data to a terminal program on the PC, but I can't use polling for...