I have the Cohesion3d board in my K40 - I recently got everything up and running, however when i send a project to the laser it cuts for a brief second then re-homes. If I press “start” again the project runs fine: this even happens when I preemptively home the machine before a cut, raster etc. (Running the Smoothie that came on the SD; its recent)
The re-home happens when the board browns out or drops the USB connection. LightBurn re-connects, then runs the home on connect behavior again. Check your USB cable, connection, and grounding for starters. Cohesion3D’s knowledge base should have troubleshooting tips for USB connection issues.