> (...)
> The manual only refers to doing this to get escalations going, however
> this is not working for me,
the escalation usually works fine :)
> and I see the intertubes sprinkled with references to setting up a
> GenericAgent.pm to handle this as well (am I correct in assuming
> this is for older versions of OTRS?).
Correct. GenericAgent.pm triggers escalation events in previous versions
of OTRS.
> Is it necessary to use a GenericAgent.pm to action escalations?
No.
> If all that is required is the Queue setup in Admin for escalations,
> how can I debug this to figure out what is failing?
You only can check ticket history (+logs) to see what is happening.
The escalation on a queue refers to all tickets in this queue. You might
check if the Escalation Rebuild Index Job (it is a Dameon Job) is running.
AFAIK this checks (and calculates) escalation times.
For more complex scenarios you might want to use commercial add ons.