Duplex GriePie Playback failure on Jack

Hello Community,
I am using a Launchpad mini that I am trying to set up with Gridpie. Sadly, when I am running Jack (no problem with Alsa) the Playback transport button flashes violently.

I went through the lua configuration file and through the default parameters but no change seemed to make a difference.
I wouldn’t believe that it is a bug, I probably have something setup in a bad way.
What is it and how can I find some kind of log file that helps you guys figure out what my pc is doing?

Thanks in advance,