This weekend I finally assembled my MMU 2.0 kit that was delivered with my Mk3 printer a couple months ago. I have downloaded the latest version of everything (prusa drivers/apps package 2.2.2, firmware 3.5.1, MMU firmware 1.0.3). I've updated the printer to 3.5.1 just fine but when I go to update the MMU unit it fails in the following manner:
I connect the USB from the laptop to the MMU and open slicer. I choose update firmware and the dialog shows the MMU COM port selected. I then select the MMU firmware and it removes the COM port drop-down and replaces it with a label that reads "Automatically detected." I then tell it to start the update and it immediately changes to a red label telling me that the MMU is not connected and to press the reset button if it is. Then the MMU seems to go through its startup sequence again. I've also tried using the 1.01 MMU firmware with the same result.
The MMU otherwise appears to function with the v0.9 firmware, I can load filament and print and eject. Is there some other trick I've missed to get this updated?