We recently converted a client law firm to Outlook 2013 running Office 365, on a AWS RDT hosted platform.
A user had set up several unique calendar category colors. About 5 in all for different daily tasks. After a few days, he notes that:
1. Some of the categories that were there and used are gone, and the affected calendar entries have returned to the default blue color.
2. Other times the categories selected have randomly changed to a different color.
3. Other times after deleting the default categories (i.e. friends, etc.), they have reappeared.
Each time he re-creates the categories, and after a few days the above problems arise again.
Note: User is also running Outlook 2007 and 2010 on different computers (in additional to 2013 on the RDT).