All contacts gone after Yosemite upgrade!

PROBLEM

I upgraded my MacBook Pro 15 (early 2011) from Mavericks to Yosemite and all my contacts disappeared.

I have about 11 000 contacts stored locally on my mac (not using icloud for this, of obvious reasons).

(Note: In system prefs under iCloud I have contacts un-checked, not wanting to sync with any other devices.)

The Contacts Application appears completely empty, however the system files seems to be there, found under:

Username/Library/Application Support/ AddressBook

RESTORING - (Temporary emergency fix.)

From this location: Username/Library/Application Support/ AddressBook I opened Time Machine and restored one recent

AddressBook folder that was backed up prior to my upgrade.

I selected "keep booth" and now had two folders: the default "AddressBook" and "AddressBook (Original)"

I closed down the Contacts Application and then I copied all the files from the restored "AddressBook (Original)" folder

over to the default "AddressBook" folder, choosing to replace all similar files.

When starting the Contacts Application ALL CONTACTS AND GROUPS ARE BACK exactly the way I want them!

BUT

When closing the Contacts application and starting it again THEY ARE ALL GONE AGAIN!

I repeated the procedure by copying the orginal files from the restored "AddressBook (Original)" folder

over to the default "AddressBook" folder, choosing to replace all similar files.

Restarted the Contacts Application with the same result: All contacts are back.

Closing the Contacts application and restarting it again: All contacts are gone.

(Obviously, for now, I can keep the Contacts Application running all the time, and try to avoid restarts but...)

EXPORTING AND IMPORTING - (Not working properly.)

I repeated the copy procedure again, got all the contacts back and selected EXPORT all contacts to a "Contacts Archive (.abbu)"

Closed the Contacts application and restarting it again: All contacts are gone.

I selected IMPORT and picked the created "Contacts Archive (.abbu)".

After some wait a random 1700 contacts out of 11 000 contacts are imported. I repeated this 3 times. Same result.

(It seems like the export is failing to include most of the contacts and the answer may be connected to the observation below)

I also exported one small group into a vCard 2,1 and 3.0 file, but when trying to importing this NOTHING happens. Nothing is imported. No message. Nada.

THE METADATA FOLDER MYSTERY:

The content of my "AddressBook (Original)" folder size is 131MB for 11 471 objects.

After copying all the content to the default "AddressBook" folder, and opening the Contacts Application (all contacts there!)

I checked the content of the "AddressBook" folder size which looks exactly the same comparing the first subfile/folder content but

now says it contains only 82MB for only 27 objects.

Turns out there is a folder called Metadata within the "AddressBook (Original)" folder.

The content of the Metadata folder seems to be all my contacts and when starting the Contacts Application they are obviously read

by the software so they appear as expected but after a 10 secs or so all the 11 471 files in that Metadata folder disappears in front of my eyes!

When opening the folder all files are gone!

I can still see all my contacts in the Application, but when restarting it, they're all gone also in the Application.

So to narrow it down it now seems to be enough to copy the original Metadata folder over to the default "AddressBook" folder

EVERY TIME before I start the Contacts Application. The Metadata folder will always be emptied by the system about 10 secs after Contacts is started.

PLEASE FIX APPLE:

1. The content of the Metadata folder is not transferred properly when migrating to Yosemite. All contacts were gone from the first boot of the system.

2. When manually putting the original Metafolder into the default "AddressBook" folder the contacts are back but are then mysteriously and automatically

erased within about 10 secs causing the next startup of the Contacts Application to again contain NOTHING.

(To be sure that it has nothing to do with an iCloud glitch I turned Wifi off so no unwanted sync could be made. Still all contacts gone.)

3. The Export and Import features does not work as intended.

Anyone experienced the same or have a solid fix for this problem?