Sim looks like it isn't cutting bottom of trough

I’m trying a test piece to make sure my bit is ok at the set speed. I’m cutting out a rectangle, all the way through the 1/2" stock. In KM simulation, it looks like it doesn’t cut to the bottom of the stock, stops at about 1/4".
This is also what happens when I cut the plywood, the trough stops at 0.27

test4.kmz (297.5 KB)

this has been fixed in production with a new KM version 3.9.4

Thanks very much, I’ll check it out.