So the procedure that was works reliably for me is:
- power off the rack
- connect the USB cable to PC
- connect the USB cable to Ansible
- hold the panel button next to the USB port on Ansible while powering the case on.
- run update commands.
- disconnect
- power cycle Ansible
I am typically on a Windows machine but just tried on a Catalina MacBook that had not been set up to work with Ansible before, ran brew install dfu-programmer, and can read/write the hex file from the command line. I found that if I forget to do exactly this sequence I always wind up getting Ansible in an odd state.
Worth also trying
dfu-programmer at32uc3b0512 read
in the terminal to see if it can find it that way? I am unfamiliar with OSX in the extreme but it would at least be a very Windows thing to decide to sandbox scripts that are double-clicked instead of running from the command line.
You also may want to try ioreg -p IOUSB after holding the panel button and powering on, to confirm that the USB device is found. For me this lists:
AT32UC3B DFU@14100000 <class AppleUSBDevice, id 0x1000022bc, registered, matched, activr, busy 0 (1 ms), retain 11>