Problem with midi-connection to digital piano

Hello!

I have an electric piano ("Thomann Digital Piano DP30") with usb-midi-functionality. I have used it for years under Windows via the USB-Midi-Connection and it always worked instantly plug-and-play as a Midi keyboard (and still does). Now, on my Macbook with M2 Max Chip and Mac OS Ventura, the usb-connection cannot be established anymore. When I turn the piano on while I am connected to the Mac it appears just briefly in the Midi-window of the 'Audio-Midi-Setup', but when refreshing the page it is already blurred out (such as if it lost connection immediately after connecting). So respectively no DAW will detect it, since the OS does not hold the connection in the first place. I would like to know if this problem is known to you and if there is any solution. It seems like a driver-incompatibility of sorts, but there are no drivers for this piano and never have been since it was always plug-and-play. Every hardware-wise cause like faulty cables can be excluded (and as I said, it still works perfectly on Windows 11). It is also no matter of having it directly connected to the Mac or via a usb-hub. (I tested all the combinations with different cables). Also my Mac is happy to accept all of the other plug-and-play-USB-Midi-devices (such as a mini midi keyboard by nektar, 'SE25') instantly without problems. 

Help would be appreciated!

Best regards

fred