I put a zero clearance insert in my Dewalt chop saw. Something must be flexing because the insert has gradually been opening up in width. I don’t know where that is coming from. The blade? The spindle? The up/down motion. (This is not a sliding saw.)
Maybe that is not an issue with the Kapex. When I want really clean cuts, I either use my table saw, radial arm saw or my picture framers’ sliding table miter saw (45 degree angle only).
I can put a piece of scrap stock under the part to be cut. That results in a very clean cut. But that scrap is “one and done”. Not worth the effort.