@metaller333 Unfortunately, other users have already reported this type of problem with kodi not starting on Rpi4 / black screen:

https://forum.recalbox.com/topic/22621/not-output-video-v7-1-1-on-kodi-rpi4-in-my-tv https://forum.recalbox.com/topic/21693/not-output-video-recalbox-7-rpi4-in-my-tv https://forum.recalbox.com/topic/22825/tearing-with-raspberry-pi4

Some users have managed to make it work by starting the kodi and disconnecting and reconnecting the HDMI cable, but it is not a practical solution, nor does it work in all cases.

The next version of Recalbox will bring many improvements, I recommend waiting to test it with the next version.