I can sign in to Outlook and other Microsoft services successfully, but I'm immediately redirected to the sign-out screen. This sometimes causes the wrong email account to open as well. I've already tried clearing cookies, but the problem keeps coming back and has also happened in other browsers and services that require regular logins. Private browsing works as a temporary workaround, but I'd prefer a permanent fix because it doesn't retain my usual cookies or signed-in accounts. I'm currently using Firefox and separate browser containers for different accounts.
3 Answers
Because private browsing works, an extension, cached session, or stored account token is the most likely cause. Try signing out of every Microsoft account in the normal window, remove the relevant site data, close all browser windows, and then sign in with only the intended account. If the issue returns, temporarily disable privacy, password-manager, and ad-blocking extensions to see whether one is altering the login flow.
The wrong account opening suggests that an existing session or saved sign-in cookie is confusing the authentication system. Since clearing cookies didn’t help, try removing only the saved cookies and site data for the affected Microsoft sign-in and Outlook domains, then restart the browser and sign in again. Also check whether the browser is restoring an old session or automatically filling a different account.
Firefox may be part of the issue, especially if enhanced tracking protection, cookie restrictions, or container settings are interfering with the redirect. Test the login in a regular Firefox window with extensions temporarily disabled, and make sure cookies and pop-ups are allowed for the Microsoft sign-in pages. If it works there, re-enable settings one at a time to find the conflict. Chromium-based browsers may also behave more reliably with some Microsoft services.
It has happened in other browsers too, so it seems intermittent rather than exclusively a Firefox problem. Private browsing does let me sign in normally, though.

I’m already separating accounts with Firefox containers, so I don’t think they’re sharing the same container, but I’ll try deleting the sign-in data for just those sites.