Problems logging in to sites

I had been using your plugin on several of the sites I was working on, but I noticed that after a few weeks of the plugin being installed, when I tried to login, I couldn’t access the admin dashboard. When this happened, after logging in, the only thing I would see, would be a bunch of links down the left side of the screen and if I clicked on any, I would get a 404 error. I had this plugin installed on 5 sites and this happened on all of them. I had ended up deleting the plugin off all my sites because when I did, the site went back to normal. But now I’m having trouble with spammers logging in and when I was using this plugin, the issue with bogus login did not happen. Now I’m assuming there is some setting that I selected that caused this issue. I’m hoping you can help me so I can use your plugin because it really did a great job.

Here are the options I selected in the admin dashboard:

On the Main Settings tab, I enabled: User White IP Access List, Block subnet and non-existing users. The rest of the settings in this tab I left. I have not changed anything else on the other tabs in this section. I also have not added my IP address. Is it important to have the ip address of all the admin users? There are several that live in other parts of the USA.

I clicked on the Antispam section and enabled comment form, registration form, other forms, and disable bot detection for logged in users.

On the reCaptcha tab, I got a site key and secret key from google’s site and enabled invisible recaptcha, registration form, lost password form, login form, wordpress comment form and Disable reCaptcha for logged in user.

This is a membership site, so I need to make sure people are not going to have problems logging in.