I think I nailed it.
I use a Steinberg UR28M audio interface.
I uninstalled everything remotely related to Steinberg, including the UR28M Usb driver and application, re installed Elements 10.30 and it worked using a generic low latency ASIO driver.
As I reinstalled the UR28M proper driver, latest version, it stopped working, no more Midi Out / Midi Thru
Now As I switch between generic Asio driver and UR28M proper driver I realize it’s the UR28M that conflicts. With that doesn’t work, without it it does.
There’s a very surprising incompatibility/conflict between those 3 elements, Cubase Elements, UR28M and Keystep.
Don’t have the faintest idea as to why. I don’t want to give up with Cubase midi editing capabilities, that I love, so I guess I’ll go for another audio board. I might send an invoice to Steinberg for the 3 days it roughly took me to get to the bottom of this . . .
Thanks all for your support / ideas.