I upgraded to 1.9 today and attempted to print some miniatures. After slicing and placing the file on the USB drive my Elegoo Mars 2P didnt recognise the file and read it as an invalid folder even though the file was a .CTB. I uninstalled 1.9 and reinstalled 1.8 Beta did exactly the same and the printer is working perfectly fine. FYI if anyone else is having the same issue.
So, it does state that you require a new firmware, for the Mars2Pro V4.4.3. My problem is, I downloaded the firmware and it is still showing the 4.3.13 in the info display.... Haven't even attempted to use CBox 1.9 yet. (I just received the printer and only did the rook test print using V1.6 so far).