Hi,
I've been looking at your Mastercam pic a little more closely. Normally the gnomic (the red/green/blue axis orientation symbol) is displayed
at or close to the work zero of Gcode. As displayed it is a considerable distance from your stock boundaries.
Go back to your Mastecam file and place the cursor on the corner of your stock and note the WCS coordinates. They should be 0,0,0.
Your description and the pic you have attached suggest to me that the corner of the stock is not 0,0,0 as it should be.
Craig