It sounds like the OEM built saftey in, IOW if you command a move with the spindle not running it will freeze, to avoid going into a cut without spindle, or if the spindle stops for any reason the feed stops.
In IPR it will automatically not move becuse you have no revs.
It works in G0, becuse the assumption is you will not program to engage the cutter in this mode.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.