In the meantime reverting to pre v2 works.
Thanks for the clue, I could not find a way to use that to make the beta testing plugin work though.
I updated WC to 3.6 with
wp plugin update woocommerce –version=dev
but there is no way back now, changing versions with the beta testing plugin still reports success, and does nothing.
It’s a little frustrating because I can see how useful it would be, but it doesn’t seem to work for me.