We’ve had one of the users reporting a really bizarre issue – all his activities have simply disappeared from CRM. The user was synchronizing with Outlook and activities are still present in the mailbox with Regarding field empty.

Thanks to Adam “Human Bing” Vero, the behavior is no longer a mystery but rather an annoying bug. After being reported by a number of people, Microsoft support stepped up and delivered a summary. Workaround is reproduced below just in case left button on your mouse does not work.

1. Instead of creating the activities in CRM, create them in Outlook and track them in CRM. I don’t know if this is a silver bullet. I know in my testing I did not experience the same behavior if I created the object in Outlook first and tracked it. My customer saw similar results as well.
2. Downgrade to Outlook 2013. This specific issue does not occur in Outlook 2013. I know we have other issues with Outlook 2013 that we need to further investigate but this specific issue does not repro in Outlook 2013.
3. Remove the delete permission on activities. Obviously this is the most intrusive as it would prevent users from being able to delete activity records. This will prevent data loss from occurring in CRM.

With 1 being too risky and 2 not being an option, I opted for 3. It’s not a bad practice anyway.