I did a little sleuthing on github, and I don't see an msd-boot branch.

I am guessing that msd-boot isn't available yet?

I used the ones in the boot folder. They had just been updated so I assumed that they were the ones. Worked fine.

Great work raspberry pi team. All looking good here when I plug SSD into USB 2.0 but no joy in USB 3.0 port. A quick internet search https://jamesachambers.com/raspberry-pi-4-usb-boot-config-guide-for-ssd-flash-drives/ suggests it's possibly my Sabrent USB/Sata Cable. Will get hold of a different br...

Adding to the config.txt file appears to have sorted all the oops kernel messages that I was getting too on my Zero W. Thanks for posting.