Yes, clearing the browser cache as you suggested did the job (both chrome and opera).  However:

1.  It can do a fresh load.  But....

2.  After I have clicked on a notification, I expect it to be removed from the notification list.  It is not.  If you cache that ajax call, browser is simply loading old server response which now is out of date?  How does user get his notifications updated?  Clear cache all the time?

3.  Why not set cache = false for that ajax call and redis cache the response server side.  That way user can get updated notification list any time he clicks on the bell and server side the list is updated once a notification item is clicked on?

Still not working for me.  It worked once yesterday for a while, and then no more.  Server still returns 400 response on js call:  inbox_notification_objects is not specified as a relationship on MobileApi::V3::InboxN

Still not working for me after I received email that problem is fixed.  After I received email, I went to the site and the very first time it worked.  But never again afterwards.

BTW, win7/Opera browser, multiple computers

Not loading for me for over a month now.  Multiple computers, multiple browsers.