In certain scenarios, the agent field is set to null (not unassigned). This ticket will not reflect in filters listing out unassigned agents and is essentially invisible from filters unless manually searched for.
Scenario example: Built-in automation “Automatically assign ticket to first responder” kicks in if an agent makes an initial response to a ticket, but is not a member of the assigned group
Alternatively, one should be able to filter null agents, but then again that’s the purpose of unassigned to begin with
