We currently have all four Advanced Configuration options turned ON at the Global-level (Channels > Email > Advanced Configuration) - including the "Show Agent name in Ticket replies and outgoing emails" option.

We also had that same option turned ON at the Department-level for every Department.  Everything was working properly - all replies used the agent's name.

Last week, we turned that option OFF in 25% of our Departments' individual configurations - all other Departments still show it as ON.  However, now ALL replies from ALL Departments have stopped using the agent's name.

After a bit of investigation, it appears that this option is the only one of the four that isn't configurable at the Department-level. 

 So, my question is: If the Global-level setting is the only one that matters for this option, then why is the Department-level switch not disabled?  Better yet, why does it even exist?  Better yet still, why does the switch on one Department affect other Departments?