Outlook email via Firefox is working for me at the moment, so hopefully that means this is not a systemic issue. I recall some time ago, Outlook would get stuck on the loading splash screen, flashing envelope icon but never going anywhere. I believe I "fixed" that issue by cleaning all Outlook.com and Microsoft.com data from the browser's cache and cookie jar. Have you tried doing that?

It's working for me as well. see screenshot Can you show what you're getting?

Is this perhaps related to [this other recent thread]? Does that one offer any useful information?

I'm having a problem with outlook as well in firefox. 124.0.1 (64-bit) Fedora 1.0

Outlook works in Chrome on same system. Just not firefox. Cleared cache - not sure what to try next

Try clearing site cookies and disabling Tracking Protection for the site.

Does it still happen in Troubleshoot Mode?

Turning off the tracking protection did it - thanks for the tip.