This is working as designed in current CA Performance Management versions.
The Search button doesn't return the item Name Alias matches because the Alias information isn't available in the Data Aggregator.
We don't synchronize the 'Name Alias' information to the Data Aggregator. That Search box sends the query to the Data Aggregator with the search string entered and compares it against Device Name, Item name, Metrics column values. It doesn't compare it against Name Alias.