OS X 10.5.4, PM 4.5.3.1
It has always bugged me how often PM refuses to update a contact sheet's contents, especially when new images have been added to the respective folder.
Often changing to a different application and back makes PM update, but often it fails and also pressing F5 or selecting View>Refresh won't help.
The last resort is closing and re-opening the contact sheet. Would love to see some improvement here.
Thomas