You have no available Unattended Bot Runners

I am not sure why but my bot runners and workflow suddenly just disappeared today. So I reconnect bot runner but I am getting this message

A new connection was requested from machine IT-4, but you have no available Unattended Bot Runners (0 used out of 0 available). Please remove Bot Runners from the “Approved” section until you have at least 1 available.

the approve button is disabled. Can I ask anyone what seems to be going on?

This was a temporary issue we had on the early morning on July 25. It is resolved now.