S5 no sound problem

Hey there fellow DJs, I’ve just bought an S5, 2nd hand since its no longer available new. And I’m experiencing a sound issue, wondering if anyone here has an idea what’s up, grateful for any leads.

When i first plugged it in my macbook pro running traktor 3.11.17, traktor recognised the controller all the controls seemed to work fine, yet i had no sound. Checked the audio setup, the s5 is selected, output routing seems fine. So started experimenting, using different techtools chroma cables, trying different usb c ports on my mac, unplugging/ replugging, restarting the s5, traktor and finally my whole mac. At some point i suddenly had sound, through all channels. Monitor and master outputs. But if I then unplug or restart anything, its gone again. Unplugging and re-plugging the controller from my mac and restarting the s5 after that, seems to work eventually when repeating this about 5 or more times.

I’ve also checked the cables and my mac ports using them with my old setup of x1 + z1 and zero connection problems there (never had issues with that setup in the past 7 years :-)
So.. whats going on? Could it be a firmware issue would reinstalling traktor 3.11 or the s5 firmware make sense? Or is it simply a dodgy usb port of the S5, (hope not!) or am missing something else?

Thanks for any help, clues, sharing of experience!