I have two computers with same version of windows and Firefox. One shows Vulnerable passwords alerts, the other doesn't. Show alerts about passwords for breached websites is selected on both

screenshot below

still looking for an answer to this, real strange I have even been comparing about:config on both machines and looking for passwords and alert

The login settings:

I leave the first two checked and remove the other two and uncheck the MSN sign box. So unless your site login is telling you got issue I wouldn't use firefox to check your password.

now neither one is working