Not All Roles Are Available Under Roles Tab When Customizing Forms

When user customizes a form, under Roles tab, user can define the form as Preferred for specific Roles. However, not all roles appear on that list.

Take note that all Roles that will appear under the Roles tab are those Roles who have permission to the record type of that form.

For example, if user is customizing a Sales Order form, under Roles tab, those Roles (both Standard and Custom Roles) that have Permission to Sales Order appear.