It seems that in the latest version of Asterisk 18 (18.8.0), the queue agents’ status is broken. If you un-register an agent and then re-register it, the agent is shown as Unavailable, and the status doesn’t get updated until the queues get reloaded.
Another strange behavior that I have noticed during the tests is that if you have to devices 100 and 101 and un-register agent 101, agent 100 is shown as unavailable.
Have any of you noticed this?