How to debug controller rumble

I’m using a ‘Nintendo Switch Pro Controller’ (clone)
I want to debug rumble to see what happens, so i modified
src/joystick/hidapi/SDL_hidapi_switch.c
uncommented #define DEBUG_RUMBLE
recompiled sdl 2.29.0
started my tool again, it rumbles, but no debug is shown in terminal
did i miss anything?