Cannot open a related preview form in a requested item
When selected, variables defined within a variable set and included in the Service Catalog do not open. When pointing to the variable, the pop-up window displays, but clicking on the preview icon produces no results.
Add a requested item reference field within the form and outside of the variable set. A reference-type form field can be created and related to the ordered item. For additional information, refer to Personalizing Forms in the ServiceNow product documentation.