Fusion 360 to uccnc issue(s?)

[AxelKay]

Issues:
I'm trying to surface my spoilboard and I saw a YouTube video on how to do it; simply the guy sets the bottom height at a negative value.
Now, some nice fella over the uccnc fb group showed me how to add the correct value within the m31 txt for the touch probe to work, but I keep getting the bit dig deep into the mdf even though the thicknessing is set to -1.5mm(!). The simulation within fusion 360 looks fine but it doesn't work the same in uccnc!
Note the coords and point of origin (no matter if it's on the lower or the highest point. It still does the same). I think I got those correct and also my post processing is set to uccnc defaults.
Thoughts?

https://www.dropbox.com/s/ya9hiyl82q2vsci/fusion-face.png?dl=0
https://www.dropbox.com/s/ckitvnt1b6qjq7f/fusion-setup.png?dl=0
https://www.dropbox.com/s/4bztlzzotivrbsn/fusion-sim.png?dl=0
https://www.dropbox.com/s/nn36gpocm3n8ua7/uccnc.png?dl=0