Have metrics with lengths greater than 20 characters and in using the search feature for the Add Metrics pop-up in Reports & Analytics... values don't return if you're searching outside the first 20 characters of the name.
Support's specific reply was...
"Yes there is limitation in the interface while adding metric, if a metric name is more then 20 character then it will append and will not show the complete name till the time you hover the mouse icon on that , so any character which is after the 20th character will not show if you try to search using that character . That's the reason we always suggest to search from first 5 character to get the exact result."
