Hi inzaratha, are you using the "old" Outlook or the "new" (beta) Outlook? For quite a while now there has been a switch/link/button above the message list to switch between them.

Have you noticed any issues with content missing or blank on other pages?

Have you considered whether you might be blocking anything:

Double-check content blockers: Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components.

Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: What happened to Tracking Protection?.

Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site.

Testing in Firefox's Safe Mode: In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Ok I could do it in safe mode so how do I determine what add on is causing the problem? It does not show the extensions or add ons in the top in safe mode. I am using the old outlook not the beta.

Unless it's a Greasemonkey user script, it probably is one of your multiple extensions related to ad blocking. You'll need to return to normal mode to experiment.

I returned to normal mode and tried each extension. Oddly enough it was the retail-me-not genie extension which finds shopping coupons. I thought it might be an ad blocking one but that is the only one that disabling it made it work again. Thanks!

Weird! but glad you solved it.