How to achieve 100% Database Sync?

Question

I have gotten most everything in Assassin's Creed IV Black Flag. 100% progress. Bought all of the ship upgrades, ship appearances, guns, swords, art, outfits, and house upgrades. I completed all of the Abstergo challenges. Etc etc.

There are 4 things I am waiting on (waiting for community challenge prizes).

1. Persian scimitars
2. Captain's wheellock pistols
3. Black and red sails
4. El Impoluto's wheel

However, I am only at 98% database sync. The above may contribute, but I feel like while I'm waiting I can work on the rest. But I don't know what's missing.

Here is the count of what I have in my database. I can go into more detail if someone can narrow down what section is lacking based on the numbers.

1. Shanties - 34
2. Documents (Manuscripts) - 20
3. Documents (Letters) - 20
4. People - 37
5. Locations - 18
6. Landmarks (Havana) - 10
7. Landmarks (Kingston) - 7
8. Landmarks (Nassau) - 2
9. Ships - 16
10. Art Collection - 50
11. Fauna - 23

I also have all of the computer hacks and sticky notes in the present day.

Update

I went through all of my crafting and fauna, and it looks like maybe "rabbit" is missing. And maybe "white whale" (but I think this is covered by "sperm whale").

Answer 1

100% sync within AC4 is not dependant upon everything available ingame. Especially the present time stuff is not required.

To check which points are missing, it is most advisable to check the "progress tracker" ingame, which mentions the side objectives which have to be completed to achieve 100% sync. 100% completion is solely tied to everything mentioned in this progress tracker.

These include all the different collectibles (Animus fragments, chests, secrets (which includes manuscripts and letters), viewpoints, shanties and the Mayan stones). Also required are the unlocks of all taverns, the defeat of the 4 legendary ships, the liberation of all forts, the completion of all assassination & naval contracts as well as the templar hunt missions.

Of course, 100% sync in all storyline missions is required as well. :-)

Answer 2

I don't know if it is counted against the 100%, but there is a 35th sea shanty that has to be unlocked in AC Initiates for it to appear in you AC4 game. Please have a look at: http://assassinscreed.ubi.com/en-gb/players/initiates/index.aspx

SPILTBLOOD AND BLACK SAIL SAILS 'MAID OF AMSTERDAM' SEA SHANTY

REDEEMABLE INSIDE ASSASSIN'S CREED IV ONCE YOU HAVE LOGGED INTO INITIATES WITH YOUR ACIV UPLAY ACCOUNT.