Too many failed login attempts after idling for two hours

Coming back to my computer after a meeting to see this message: “Too many failed login attempts. Please try again in 24 hours.” No one even touched my computer. Just two days ago we have turned off Jet-Pack’s new security feature which somehow always include our IPs in its blacklist. Now it’s this. We have not installed any new security plugins. We have always have Limited Login, Custom Login and Login-Logout that are related to login. They have been working together for almost a year now.

Any insights or similar experience? How can this be solved?