I’ve had headaches with getting printf working.
There are some examples under CubeMX that work for the example.
When I do the same examples under another project they don’t work, and the ST-Link doesn’t step into the function either.
When printf is connected with HAL_UART_Transmit() it pends on the charaters being sent.
With the HAL_UART_Transmit_IT(), it transmit a user supplied buffer, but its not a circular buffer, so if a 2nd printf is invoked before the first buffer is empty, it looks to me like it would fail.
Technically since its CubeMX I think the place to ask is
I’m currently trying an embedded derivative xprint and tying into a circular buffer - probably my own but another example here