Hi Stan
Thanks for your tips! OK - so I checked within the sensitivities and yes - MSFS “sees” my flap lever and it works as intended.
Until now I was dead sure I have to bind to the “Spoiler Axis 0-100%”. Because - well - it makes sense right?
But in fact, once I bound it to “Spoiler Axis” - it worked! Bam! Just like that haha!
Now, what Spoiler Axis 0-100% is - I guess Trump would say: “Nobody knows why” But hey - as long as it works!
Thanks again 
best
Merlin