Hi @habasud
There is a similar discussion here ( Pocket Reform Keyboard disconnects and crashes ).
My take so far is that is mostly an incorrectly seated cable or a faulty keyboard. Mine still has this problem once in a while depending on how I wiggle the pocket and the hinges position. Also tends to go away for a bit if I open and re-seat the cables.
An easy test is also to check if the keyboard drives the OLED menu cleanly but you can´t type in the system. Which, as far as I understand, mostly means the Keyboard is alive and well but the USB connection failed.