[Karamazov]

Originally Posted by kovidgoyal

Run from source wont work for this, as it is a change in native code not python.
You can try the beta builds from here: https://download.calibre-ebook.com/betas/

That did the trick the scribe is recognized by Calibre and I can upload books as expected. The only delta is that it seems Calibre is refreshing the entire device library at each connection (Between one and two minutes) but I guess it is a consequence of this new firmware and MTP. At least the connection issue is fixed. Thanks a lot for your quick help on this!