I really don’t have a clue how I did it, really not, but things work like they should now!
The Pyramid finally showed up in my MIDI devices list / DAW on my computer, sending notes out via USB successfully.
Also, when I connect the Pyramid to the USB HOST jack of my MIO10 interface (to use Pyramid without a computer), I finally can send notes out from Pyramid USB to the other DIN sockets of my MIO10 interface.
Connecting the Pyramid to the MPC live is also working fine now.
No crashes anymore when using USB, no problems sending out MIDI data via USB anymore.
Seems to me it was some kind of a weird Pyramid / USB bug.
Hope things stay fine now…
Thanks for trying to help!