Hi @Leonard,
If agent is set to none in the same group, the Auto assignment will not assign it to the next available agent
You must turn on the Auto-assignment feature for the group if you want to assign tickets to agents. You can turn on the Auto-assignment feature inside a group by going to Admin→Groups—>Group Name→Edit Group—>Auto Assignment. The Auto Assignment will work only when the Automatic Ticket Assignment is turned on.

Cheers!
Aravindsrihari B V
Hello Leonard,
Adding to Aravindsrihari’s suggestion, please also verify whether the agents in the specific group had their “Agent Availability” toggle ON at the time when the ticket was assigned to the group.
If none of the agents in the group has their availability toggle ON, the ticket would still continue to be in Unassigned state even if the group has ‘Auto Assignment’ option set as ON.
Thanks for the responses. To clarify, yes, I still occasionally get a few unassigned tickets in groups that are in fact set to “auto-assign” and there is agent availability, (that is, there are in fact agents with “auto-assign” turned on, on their profiles).
Since posting, I have found out that we have at least one automator (created long before I arrived) that assigns tickets to a group, then specifically set agent to “none.” Also, an agent can assign a ticket to a group, and if they actually dropdown the list of agents, and click on the “...” it will save the ticket and remain without an agent. If they just assign to the group and not enter the agent field at all, then it auto assigns.
@Leonard - Ah, this makes sense now. Workflow with the action block “Assign to agent - None” is the reason then.
Regarding the scenario where agents manually choose “...”, you can configure a separate ticket workflow with event “When agent is updated from Any to None”, and action node, “ Assign to Agent - Event performing agent. This will assign the ticket to the agent who performs the action to set the agent field as blank.