I have exactly the same problem today. I got a notification that 3,333 files have been added (which I think are the original WP files, because the scan date is last Friday when I first installed the plugin) but when I try to look past page 1 of the log, I get the same error and it returns me to the first page again:
Fatal error: Call to undefined method WP_Error::get_items() in /home/becomeyo/public_html/wp-content/plugins/better-wp-security/lib/bit51/bit51.php on line 353
My site looks fine however, I think the issue is because of the number of log pages.