That can happen if your VFD has gone into a fault state. Check the readout on the VFD (inside the cabinet) to see if there are any errors)
No errors in the vfd
the spindle starts up fine while doing the spindle warmup
You could go ito the Mach settings and try to invert the spindle fault signal. I don’t know exactly where that setting is off the top of my head, if you can’t find it message support and they can sort you out