I had some progress!
I have checked and re-plugged all connectors but it did not help. Connectors seem to be clean and tight fitting, no corrosion, etc.
Then I have taken my meter and started checking voltages on the CMD connector. After I have measured and checked everything including +5V supply voltage on pin 5 I have tried to connect to the drive and magically connection did happen this time.
I have no explanation to this. I hope it was some sort of latch-up of either optocouplers or FTDI cable.
scrambled, does VSD-E really need HV supply to establish communication with the PC? I was able to connect to VSD-A and observe drive information including undervoltage fault condition with only logic supply and FTDI cable.