Ok Folks,
The following is a simple thing and all you want to do is cut the slots out ( offsets required ) using a 0.125" diameter ( nothing else allowed ) end mill and .270" deep.
Keep it as drawn, including the start point, there is nothing wrong with the attached dxf.
It's just four elongated holes in a plate. Sometimes LC just dosen't like something and multiple elongated slots are one of them.
I did get it to work , but it was a challenge......... so heck, i figured it would be something for folks to play with.
HAVE FUN,
RICH