After a very brief play it seems like the singular transit option is the way, and the shortest cable of the highest quality helps. I have found that for bracketing several steps seem to work for me ....
- Select USB tethering option in camera menu
- Select Data and no power in menu ( just below ala Hat)
- Select Focus bracketing in the camera top left button first but thats all
- Connect computer with good USB C to C keep as short as poss.
- Wait for camera to be recognised and select live view
- Click on screen of computer to select the nearest point first, allow time to locate and for the screen display to show the distance scale ( below live view)
- Take the top dropper and click on the front point selected, it should locate this and show a distance on its slider.
- Repeat by finger/mouse clicking on the furthest point, then select with lower dropper again waiting for it to register and show the distance scale.
When selecting focus points it is easy to think you can go to the edge of the display, but the truth is it has to be within the bounds of the focus points , so allow room for a soft edge if focus is critical. Zoom is still not working whilst bracketing , and its still a bit clunky , but hey this is progress........ well enough for me to consider a Pro grade tether cable.