Have you check your PLC logic?

Are you doing this operation first time? i.e. have you faced this problem recently or first time?

Check your PLC logic, how is it switched ON? i.e. in AUTO mode generally M code is used to switch ON coolent & in part program the same M code is called to switch ON coolant. So check PLC logic if spindle ON interlock is incorporated. If yes, you need to modify your PLC logic so that in case of spindle OFF also coolant be swithched ON.

HTH