I suggest trying a few things:
1) Try to export views/reports and see if the issue occurs for those as well.
2) Check that there's nothing relevant in the Archive folder.
3) Did you connect to the management IP or the SmartEvent (if not on the same server)? If this is distributed try to repeat the operation from the other server.
4) You can try to restart the SmartView processes by using $RTDIR/scripts/stopSmartView ; $RTDIR/scripts/startSmartView and see if this solves the issue.
If nothing helps, perhaps the best way to continue is to open ticket for support.
Kind regards, Amir Senn