Make certain that you are looking in the proper section - cash game data ($) and tournament data (T) are separated so if you have imported only one type of data you would not see it in the other section. If you are in the right section check that
'Show Marked Hands Only' is not enabled and that the dropdown next to it says 'No Tags Selected:
Guide: Tagging HandsIf no tags are enabled right-click the empty hand report and choose 'Configure Report'. In the window that appears, click 'Restore to Default -> OK' and see if that fixes it.