Auto Contact Linking logic in BB 10

Hi,

This is driving me up a wall to a certain extent. Furthermore there is no documentation on how this works OR how it is supposed to work.

Here is my scenario:

1. Local Outlook Contacts
2. Gmail Contacts
3. Outlook.com Contacts

The source for all 3 contact lists is GMAIL, but have also tested with the others as source (Outlook.com OR Outlook)

They are kept in sync via Google GO Contact Sync Mod (open source). I am confident and double checked that they all have the exact same data in the correct fields (via CSV exports).

Since then on my Z10, I have completely deleted Google/Gmail, therefore there are only 2 email accounts, address books and calendars (Outlook.com & Local Outlook Address book coming from BES)

Outcome:

1. Most contacts auto-link, but I notice the exact same contacts have to be manually linked to be the same each time I was testing.
2. After some time, they auto unlink, and have to manually relink the same contacts again.

What's going on here, and where is the documentation/tips to ensure my address books meet the BB10 auto-link requirements?

Thanks for any help on this.

Regards.