Setting the default value of the "Assigned to" in the interaction table breaks the Advanced Work Assignment.
The available Agent cannot receive any chat request notification.
In OOB instance, when an end-user contact Live Agents, an Interaction record and a Work Item record will be created.
The "Assigned to" is empty and the "State" is New for the interaction record.
if the default value of the "Assigned to" is set, the "Assigned to" will be the default value and "State" will be set to "Work in Progress" automatically.
The Work Item record will not be created since the interaction is already in "Work in Progress" State.
As a result, the Agent will not receive any chat request notification on the Agent Workspace.
Be careful when setting the Assigned to default value of the Interaction table.