When the user submits the wrong credentials they don't see an error message or anything else. They just get a white screen containing nothing.
I created a new plugins folder and moved each plugin one-by-one to see which causes this problem. When I moved Defender it started working good.
I set WP_DEBUG to True in wp-config.php to see if there was a message, but nothing to see.
Hope this can be solved, cause I like the plugin!