Customer reports when they are submitting a form in Service Catalog, fields are not being populated with the provided information.
This has always been an issue and has never worked correctly before.
The script for the offering was not written correctly.
Release : 17.3
Component : SDM - Catalog
Correcting the code written in the script allowed the fields to be populated correctly.
Try importing a copy of the offering into your lab environment to see if the issue persists.
If the issue persists in the lab environment have the customer reexamine their code.