As you can see, my inbox shows (and has shown for months) 56 unread messages, when in fact there are none. I've used different browsers, different computers, cleared cookies and cache, etc. This is not a client-side issue. 

This issue persists on the web version, but the mobile version does not display any such unread count. 

Anyone have any ideas?

EDIT: Further, while trying to post this question on Chrome, it persistently tells me that I haven't filled out all of the fields and won't let me post. 

Outlook.com is one of the most poorly designed Microsoft sites I've ever seen. Again, this is an issue that persists on multiple systems and after clearing cookies, cache, etc.