Slot: Tangential Fragment Extension not working

[FrodoLoggins]

Result with no tangential fragment extension specified:

Result with a 1" tangential fragment extension specified:

[pavmed]

The reason F cannot extend your slot is that you choose closed pocket as seen in Geometry tab

When pocket is closed, technically it has no space where to extend. Is you'd like to make use of Tangential extension option you could use 2d contour toolpath.

Slot toolpath can make extension only if you select open pocket as in the screenshot