Creating a ticket in Service Desk doesn't set $dto.actor.displayName correctly

I have a HipChat notification set up when tickets are created in JIRA. This works correctly except when new tickets are opened in Service Desk. Instead of seeing the Reporter name in the message e.g:

REF-123: Migrate x to y →Create Issue→Open by Joe Bloggs. Current assignee is John Smith.

I see the reporter name as $dto.actor.displayName, e.g:

REF-123: Migrate x to y →Create Issue→Open by Joe Bloggs. Current assignee is $dto.actor.displayName.