USART Tx not working on F446RE Nucleo 64

[matutef1]

Hello, this is my first grblHAL attempt. I'm building a F446RE Nucleo 64 + Protoneer v3 with pretty stock configuration.

I enabled the #define BOARD_PROTONEER_3XX in my_machine.h, disabled #define USB_SERIAL_CDC just in case and set #define SPINDLE0_ENABLE SPINDLE_NONE since I saw it was using the UART Tx pin, so I wanted to discard that issue.

Firmware seems to be running good, I put some breakpoints on UART0_IRQHandler and they're hit as expected, received data is ok, but nothing is transmitted back.

Any help will be appreciated.
Thanks!

[terjeio]

Comment out AUXOUTPUT0 port and pin