This can be caused by checking the “reoccurring” check box in the schedule section and then leaving the option on “Daily”. The “reoccurring” check box only needs to be check if you plan on using the “Weekly” option. If you want the schedule to just play messages every day then leave the “reoccurring” check box unchecked.

To solve: Delete the current schedule. Then create a new schedule as normal just without checking the “reoccurring” check box. Finally, upload the new schedule to the sign.