@lpassamonte not sure if you’re even still here or trying this but I just joined so gonna necro the thread.
Probably better for you to post rpi specific questions in the raspberry pi forums, and a quick google search found this thread that might solve your issue: https://www.raspberrypi.org/forums/viewtopic.php?t=5107
Basically they had to edit the config file and enable a couple of HDMI boot options. Good luck!