If a job is set to execute recurring and the promptset value within the job is modified, the next generation of the job does not pick up the changes to the value.
This behavior has been confirmed as by design. The values set within a prompt for a period container (C_PERIOD via execute recurring or a PERIOD object itself) are saved for the run of the container. Other object information is processed at time of the execution, but the prompt data is not.
Use ACTIVATE_UC_OBJECT within a Time Event, which picks up all changes per execution.