SOLUTION:
Density of the design is too thick and must be lightened.  The needle and thread will basically rip through the leather and cause a hole slightly larger than the needle diameter.  When stitch penetrations are too close together, this causes a slice.  Lighten the density and lengthen the stitch length.

If more coverage is needed under satin stitching, set in a light zig zag underlay with a narrower width under the columns.  If more coverage is needed under fills, the addition of underlay does not work well, as it only adds excess penetrations in the leather.  Try switching to a 30 Wt. thread or use a stabilizer similar to the color of the thread as a topping under fills that require solid color.