While using Zimbra Desktop on a Mac (not sure it that matters), periodically when I go to Address Book, all of my Contacts are missing. I have to double click on the word "Contacts" for them to re-appear. This happens frequently while using Zimbra throughout the day.

Background
Zimbra Desktop 7.2.1 on Mac
Two Zimbra Accounts added. Only one of them have all of the contacts.

Everything else seems to work fine.