Some sort of Z axis problem (I think!)

Hi

I'm very new to this so please bear with me if this question is a bit "noddy". I've built my WorkBee and I'm trying to make my first few cuts to check I've got a vague idea what I'm doing. I've created a test cut in Carbide Pro and uploaded the G-Code to the controller. However whereas I should be creating a shallow "square" cut (1mm deep) into my piece of MDF, the machine is dropping to make the cut, creating a small 1mm or so hole in the MDF and then backing away. I'm guessing it's a machine limits type problem but the console is not reporting an error.

My G-Code look like this:

G90

G21

(Toolpath:...)

;M05

;M0 ;T251

;M03S18000

G0X-14.855Y-14.822

Z0.250

G1Z-0.381F254.0

Y14.828F1219.2

X14.795

Y-14.822

X-14.855

Z-0.762

Y14.828

X14.795

Y-14.822

X-14.855

Z-1.000

Y14.828

X14.795

Y-14.822

X-14.855

Z20.000

;M05

;M02

Console output shows:

10/05/2024, 10:24:42Finished printing file 0:/gcodes/testcut.nc, print time was 0h 0m10/05/2024, 10:24:35M32 "0:/gcodes/testcut.nc"
File 0:/gcodes/testcut.nc selected for printing

My dashboard shows:

Any good ideas of what I'm doing wrong?

Thanks

Gary

Total Newbie, treat me like an idiot and chances are you won't go wrong! :)