John(s).. Deleting the cache files does not solve the problem. If you had success with this method, it is most definitely not universal. I have tried every combination of cache file deletion, as well as complete obliteration of files on a computer, clean-install, etc..
The problem is with the account in conjunction with an Apple OS installatiopn. With my experience (ran an Exchange 2010 server) is there are different settings based on devices and device IDs, that are kept by the server, for control like remote wipe, etc.. I think there is a little more to it when it comes to the "outlook365.com" service and this particular problem.
The problem only affects the use of the OS X Calendar application. The problem is not apparent in iOS devices yet. I do not have any Android devices to test with (if possible), or the use of the Outlook for Macintosh application on the same computer (which works..)
This problem also became apparent only after "TimeProfile" calendar showed up (and a mistakenly deleted - or attempted). I never had a problem with this calendar sync feature until the the fateful day I mistakenly attempted to delete the "TimeProfile" calendar. Ugh!
I am happy to troubleshoot with any M$ people who want my help.