When trying to order the "Mark XXIX: Extremis Suit" catalog item in the Service Portal as user "tony.stark", after clicking the order button, the request hangs and a horizontal straw-sized modal comes up and does nothing. The user wanted to know why this is.
The issue is that the user ("tony.stark") does not have access to the modal which is trying to load (which admins can see). The modal is just a widget - "Catalog Checkout":
Whatever roles user "tony.stark" has is what will need to be added to the "Roles" field (top right of the page, third row down) to enable access for Tony - unless...
...Unless the Service Portal User Criteria Support plugin (com.glide.service-portal.user-criteria) is installed in the instance of concern. If this is the case, the below-associated system property needs to be set to "true":
Then, user criteria can be utilized to allow Tony to see the modal (widget "Catalog Checkout"). In this case, Roles will not be used.
By making these changes, the user can resolve the issue and allow access to whoever they want to have access, according to their use-case and business need.