EBB36 v1.2 USB flash

I'm trying my hardest and searching I promise.
I'm trying to flash via usb in dfu mode. I configured per the v1.2 manual. Device shows as STMicroelectronics STM Device in DFU Mode. I am not using canbus, I intend to use this in USB as a traditional mcu.

Flash fails
Flashing out/klipper.bin to 0483:df11
sudo dfu-util -d ,0483:df11 -R -a 0 -s 0x8000000:leave -D out/klipper.bin

dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

dfu-util: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release!!!
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 1024
DfuSe interface name: "Internal Flash "
Downloading to address = 0x08000000, size = 28528
Download [=========================] 100% 28528 bytes
Download done.
File downloaded successfully
dfu-util: Error during download get_status

Failed to flash to 0483:df11: Error running dfu-util

Start with the EBB v1.2 manual and reproduce the reported dfu-util command using out/klipper.bin against USB device 0483:df11. Investigate the reported Invalid DFU suffix signature and get_status failure, then confirm the documented USB flashing flow completes successfully without the final error.

Written by the indexing model from the issue text.