Why can't I create a constraint on a custom description property?

Summary:

I have a custom property for a description that is on my segments within an application. According to the user guide "You can create constraints for a property that meets these criteria:

• The property must be a node level property. You cannot create a constraint on a relationship level property.
• The property data type must be a string, numeric string, or a sequence data type.
• The property value cannot be inherited, and it cannot have a Derived or Derived and Stored default value"

My property meets these criteria. However, it does not show up in the pick list when trying to create the constraint.