I am running Fusion 360, UGS, GRBL(on an original Arduino UNO R3). I have POSTed many tool paths since building my machine and have never encountered this error.
Fusion generated a 97000 line tool path. When I run UGS in check mode I get the error seen in the attached picture.

Attachment 429156

Have any of you encountered this and fixed it?
Attached is the Fusion file if you care to look at how it is set up.
The tool path giving me the error is called 2D pocket1 (2). All the others run fine.

Thanks