Dependent variable (eg. Subcategory ) does not have a value on the Service Portal when populated via a script
The value assigned to the Subcategory is dependent on a different Category than the one that was selected. For example, a "Laptop" belongs to the Hardware category but there is a script that sets the Category to "Software" and Subcategory as "Laptop". The system will allow the record to be created, the Platform UI will show the values when the record is created but the Service Portal will not.
Confirm that the Category/Subcategory have the right relationship.