We have reticently discovered that when Orion triggers a CPU or Memory Alert on Switch Stack, it is using the average CPU or Memory for all switches in the Stack. So if you have one switch running at 99% and four switches running at 10%, you will never be alerted to an issue. When looking at the stack details, Orion is able to see the individual values for CPU and Memory but there does not seem to be any easy way to create an alert for these. I have recently gone through some troubleshooting with SolarWinds support and they confirmed.
I would like to see an easy way to build an alert for Switch Stack Members that lets you alert on the CPU and Memory values of the individual Switches.... Along with being able to identify which switch in the stack the values are associated with..