Only new logins shown and sorting doesn't work

The plugin only shows the last login date if the login occurred after the plugin was installed. But I guess WP doesn’t keep that information by default?

Sorting by last login doesn’nt work for me. I have just installed the plugin, and my own user is the only one that has logged in since then. I would expect my username to show at either the top or at the bottom of the list, depending on sort order, but the list appears to be sorted by username, independent of last login time, just as if I clicked the Username column for sorting.