Have you tried using RDWorks to see if it behaves the same? If it does, then it would be a machine setting or firmware issue. If it behaves differently, then it would be a software issue, so it’s worth checking.
I’ve just tried to run a job on the 6445 with the rotary enabled, and both from RDWorks and LightBurn pressing the Start button has no effect, so this appears to be an issue with the firmware, not software.