Directory Synchronization issues for Office 365 users accounts

Check the Metaverse tab, search for particular user there and check the properties to find out if/why he has been filtered out. This article lists the attributes that need to be configured for a user to be synced: http://social.technet.microsoft.com/wiki/contents/articles/19901.dirsync-list-of-attributes-that-are-synced-by-the-azure-active-directory-sync-tool.aspx#How_directory_synchronization_determines_what_isn_t_synced_from_the_on-premises_environment_to_Windows_Azure_AD

And of course, double-check if any additional filtering is in place.

I've taken a sample of users who should be synched:

User objects are filtered if:
•mailNickName starts with "SystemMailbox{" -checked not relevant
•mailNickName starts with "CAS_" AND mailNickName contains "{"  -checked not relevant
•sAMAccountName starts with "CAS_" AND sAMAccountName has "}"  -checked not relevant
•sAMAccountName equals "SUPPORT_388945a0" -checked not relevant
•sAMAccountName equals "MSOL_AD_Sync" -checked not relevant
•sAMAccountName isn't present -checked They all have one
•isCriticalSystemObject is present -checked  <not set>
•msExchRecipientTypeDetails == (0x1000 OR 0x2000 OR 0x4000 OR 0x400000 OR 0x800000 OR 0x1000000 OR 0x20000000) - checked. No attribute. Exchange has never been installed in this domain


With regards to filtering:
I have setup AD DirSync only to sync users beneath a certain OU. THis OU contains all the users I wish to synchronize. I've checked this again and it looks correct.
When I installed DirSync I asked it to synchronize the members of a group "gOffice365Accounts".  Users are members of this group. I cannot see how to change this.

The group I am using does not have nested groups.

I certainly did miss the part about not supported in production. Would you recommend uninstalling and installing an earlier version?

I've looked on the Metaverse Search tab and checked a sample user.  I cannot see anything about filtering.

I had opened a ticket to Microsoft for a solution to this. Their engineer took control of my session and did some Magic, of which I was unable to follow it all, and things now work.

Thank you Microsoft and thank you Vasil for your help. I only wish I could report back on what Microsoft actually did to fix things.

Apart from Microsoft doing the final fix, This was the most helpful information.

Oo they are allowed to use remote control now? :)