PM Calendar Generation ORA-01841: (full) year must be between -4713 and +9999, and not be 0

Our maintenance pm calendar generation has been failing for the last couple days, and we can no longer get into Maintenance Plan on a PM Action. I have narrowed it down to the PM Plan Horizon definition.

I believe it was setup this way to not have to remember to update this every year or so. 

In our test environment I have changed this value to 2025, and all is well. But I can’t change it back without unchecking the Validation Enabled box.

Specifically it fails here in the Maintenance_Configuration_API:

FUNCTION Get_Def_Dem_Mat_Horizon RETURN NUMBER
IS
   
   FUNCTION Core RETURN NUMBER
   IS
        mat_horizon_ NUMBER;
   BEGIN
      mat_horizon_ := TO_DATE( Object_Property_API.Get_Value('MaintenanceConfiguration', '*', 'PM_PLAN_HORIZON')||'12'||'31','YYYYMMDD')- SYSDATE;
   RETURN mat_horizon_;
   END Core;

BEGIN
   RETURN Core;
END Get_Def_Dem_Mat_Horizon;

This has not been changed for my guess is 2+ years.

Any idea on how to keep it dynamically updating?

Is this related to leap year?