Since the Berlin release, it is no longer possible to drill through Reference Icons that are in variables. This is expected behavior.

1. Navigate to Service Catalog > Can We Help You? >Create a New Incident.
2. Enter a name in Open on behalf of this user field.
3. Look up the newly created incident.
4. Go to the variable section.
5. Try to dril through Reference Icon.

Hover over the icon to view the referenced record.