I purchased the Gold Edition of Assassin's Creed IV: Black Flag, which comes with the season pass. If I look in my DLC list, it lists:

1. Crusader & Florentine Pack (SP)
2. Death Vessel Pack (SP)
3. Freedom Cry (SP)
4. Illustrious Pirates Pack (SP)
5. Season Pass
6. Gold Edition Activation Key
7. Activities Pack
8. Collectibles Pack
9. Resources Pack
10. Technology Pack

However, if I look on the actual Steam page for the game, according to Steam at least, I don't own the following DLCs and am able to purchase them:

1. Freedom Cry*
2. MP Character Pack: Blackbeard's Wrath
3. Illustrious Pirates Pack*
4. Guild of Rogues

As you can see above, some of these I already own (they're listed in my game's DLC section), yet it says I don't own them on the Steam page.

THIS HAS BEEN AN ISSUE WITH UBISOFT GAMES FOR MONTHS, IF NOT YEARS! HOW HAVE YOU GUYS NOT FIXED THIS BY NOW?! I've experienced the SAME issues with Tom Clancy's Splinter Cell: Blacklist, Far Cry 3, & Trials Fusion:

https://steamcommunity.com/app/23560...5336602229278/

https://steamcommunity.com/app/24205...0730761009333/

https://steamcommunity.com/app/22024...4591486721212/

https://steamcommunity.com/app/24549...2755236415470/