Seems that there is a bug in the usage of the tabs option. Having set your material depth (in this case 10.5mm), create a shape and set it’s cut depth to 10.5mm by typing the value into the editfield and hit return (which would seem the logical GUI option ?) - no tab option. The slider control is OK, but not really an accurate way to set the depth value?
If you then move the slider to it’s lowest position, the tab option pane appears - seems a bit inconsistent.
You also can’t set the cut depth to be below the material depth - not all materials exhibit the same depth over their surface and it’s necessary occasionally to cut below the indicated figure to ensure it cuts through - a warning that you are doing it is fine, but not to have it disallowed ?