The attached mpc is from a bigger project, but I removed the other stuff and just left the failing vector cut. The vector looks fine in Designer, but as you can see goes haywire when machined, adding additional vectors. The vectors were all drawn with Designer 1.187 and cut with 1.187 firmware, but I also loaded the project into Designer 2.004 and ran that firmware with the same result.
I must say, this really ticked me off, as there was 1/2 hour of carving ahead of this, and it was being carved on a glued-up blank that also took a lot of time to prepare. Bad words were spoken.
Trying to finish a large project with many parts so I am going to try to find a work around, maybe break up the single vector into parts, separating the vertices where things went wrong. But this should also be investigated as a bug.