As the Service is many to many relationship, the validation rule would not work if the main object is not yet saved. Therefore, we will allow to save the Change with the Status "Logged", but in the moment the Status is changed, the validation rule will check that at least a Service is linked.
Please use the following expression for the validation rule:
$(if ChildFold("Change#", RecId, "CI#Service", "1", "+") < 1 &&
Status != "Logged"