Hi, lucytech!
‘Last login’ feature is not provided by WP, that is why it is based on side plugins like ‘user-login-history’, or ‘wp-last-login’, or ‘when-last-login’. Also Inactive User Deleter collects those data by its own if there is no of any such plugins. But problem is that initially any of plugins above doesn’t have any data right after installation. They should be installed then earlier then better and they will collect necessary data during site life (logging user log-ins-and-outs).
If we have ‘inactive user’ case then we don’t have data for that user at all. So i may give a piece of advice – wait for some time (week, month or what period is suitable for you) and then filter users by ‘user has no known date log-in.’ criteria. It will give you the list of users who didn’t log-in starting from the plugin installation date.
