Trouble flashing NVM

[DatanoiseTV]

I've made a board which uses the STUSB4500 and trying to flash it with a Arduino Duemilanove with SoftWire Wire(A0, A1) but it fails.

Press 'f' to flash the configuration ...
Flashing - hang on ...
Failed to set user password
FAILED flashing :(

Do you have any hints?

[DatanoiseTV]

Now flashing was successful, but even though my USB PSU supports PD and is able to negotiate 15V or 20V with other devices, it fails to negotiate:

Schematic: https://imgur.com/pJCw2jW