[fritsch]

Good. I think we have to end this here. There is nothing left I can do for you.

 OK... Would you care to explain?

And who can I turn to, now?  

 Your issue has zero to do with kodi. Whatever happens is only happening for you on your installed / configured system. Clean installations with e.g. LibreELEC proved that. We asked many others running Ubuntu (including me) to test your samples. No one had that issue (Edit and most importantly there is absolutely no correlation with anything in kodi's log.