tried several systems: HPz840 win10/64 latest with onboard usb3 and third party USB-c, ASUS Laptop (1-year-old, win 10/64 latest) with USB 3 and USB c, MacBook pro 2017 tb3/USB-c ports with different cables original from DJI and several thunderbolt/USB-c third-party/apple, mac mini m1, nothing works anymore, the SSD will show up as unformatted/uninitialized
but the smart remote from the m3cine does playback and sees the files on the internal SSD...
is there any other way to copy/rescue those prores files?

all other USB devices work perfectly with all of my computers!!!

Yea same issue here, look at other threads, lots of them.
People have issues connecting/reading the internal SSD on the Cine on both Windows and  Mac machines.
Best bet is to return the drone and ask for a refund, DJI do not understand the issue and a not currently working to fix it

Had this issue when I first tried to connect to my Mac, not showing up and not trying to mount it either, Windows 10 machine had a similar problem, would get the Windows tone for connect, follow by the disconnect.

Connected it via USB-USB-C and it suddenly started working, after that it was no problem, USB-C - USB-C DJI cable also working, went back to my Mac, and its also now working every time. Guess some sort of parameter glitch within the drone as it wouldn't work on any machine, but once it started working on one it works on everything now.

SSD read works an Win10, but very slow

i use the USB C 3.1 2GEN on my Asus ROG Strix370-F, but it is slow :-( and i think 3A Power for charging is to less