Over the last two weeks a number of calendar items and messages (both sent and retrieved) have been disappearing from my Outlook 2011 for Mac. I have rebuilt the database and they don't return. In some cases I remember some of the text and search it with Spotlight and it finds a message but when I try to open it I get the message "Outlook cannot open the file because it is not associated with the default identity." However, I have only one identity (Main Identity).

I am using Outlook for Mac V 14.6.0 and Mac OS X 10.10.5