The most common cause of that is having a filter enabled. That could be a filter in the sidebar on the left, so make sure that all of those are cleared, but more likely is that you have either 'Show Marked Hands Only' enabled, or you have a tag selected in the dropdown list next to that (these options are shown just above the hand report). Clear 'Show Marked Hands Only' and if it says (for example) "1 tag select" open the dropdown and remove the checkmark next to any tags that are selected.
If that doesn't help please attach a screenshot
of the full PT4 window either here or in a Support Ticket
so that we can see what is going on.