Ok turning the cable 180º around it does work!
In my case, the brand label up.

So, now I'm curious what happened to the whole "it doesn't matter which way you plug your cable in" thing from USB-C here.

I'm using a MacBook Pro 15" from 2018 which has only USB-C ports so I was delighted to see M5Stack using USB-C connections as well. Nonetheless my USB-C cable does not work with it. And neither does a USB-C to A adapter.

What does work Is the USB-C to B adapter connected to an Anker USB-A hub and then connect the USB-C to A cable from M5Stack to the Basic Dev Kit. Surely this must be easier to do right?