For several PowerCLI objects that are a default set of properties that are displayed in the console.
This is controlled through the .ps1xml files.
Unfortunately, the IsoPath property is not included.
With Format-List all the properties are displayed.
An alternative is to use the Select-Object cmdlet and explicitely select the properties you want to see.
For example:
Get-VM Test1 | Get-CDDrive | Select Name,IsoPath