Sometimes, the column names you see when you run cmdlets do not really correspond with the true object property names. For example, Get-Process will create a column named "CPU(s)," and Get-EventLog will display a column named "Time." However, when you try and use Select-Object, Sort-Object, or Format-Table on these column names, you will get empty columns because they do not really exist.
The true property names are returned when you pipe results to Select-Object *. As it turns out, "CPU(s)" really is called "CPU," and "Time" is really "TimeWritten."