The M code is waiting for a Finish (FIN) signal. Until it sees one nothing is going to happen.
Spare M codes are more of a thing then an idea. Meaning they activate auxiliary functions which normally include wires, relays, connections etc. You have to look closely in your electrical manual to see if you have any available already. Finding and returning a Finish signal has been the bane of spare M code users for a long time. Including with me.