Redeemed a Obsidian 6-pack Sea of Thvies on Xbox App, but own game on steam and items do...

Yes, i am having the same problem and have not received my 4 items in-game. The Stream was the on the 10th of June and it is now the 27th of June. This is 17 days later (2 weeks and 3 days) I have gotten another Xbox message that i have received it and that
it should be found in my equipment chest in game yet i check and do not see the 4 items. Maybe the issue is that i already had the obsidian drum and onyx compass from previous mixer rewards. But i do not have all the items in the onyx 4 pack. I have closed
and reopened the game to see as well. For reference i will copy and paste both Xbox messages in quotation marks.

"Thank you for watching 'Sea of Thieves: Mixer Invitational – Battle for LA' on Mixer during E3 2019! You have earned your free Onyx Four Pack. Please check your 'My Games and Apps' section on your Xbox One to install.​" June 10

"Thanks for watching Sea of Thieves: Mixer Invitational – Battle for LA. Your Onyx Four Pack MixPot is ready and waiting in the game—sorry for the confusion. Launch Sea of Thieves and you’ll find these four items in the Equipment Chest: Onyx Bucket, Onyx
Compass, Obsidian Drum, and Black Dog Concertina." June 27

Hey matus0405,

By watching the Inside Xbox - X018 show on Mixer, you were eligible for a chance to receive a MixPot that included an exclusive custom "Forza Horizon 4 Limited Edition Festival Tee” top, Sea of Thieves Obsidian
Drum, and the Sea of Thieves Obsidian Spyglass.

To redeem this content:

• You will need to make sure this shirt content is installed in the "Manage Add Ons" section for Forza in the "My Games and Apps" section before you boot up Forza Horizon 4 or Sea of Thieves. Once in game, head to your character customization screen, and
  it will be available in the "Tops" section.
• Sea of Thieves add on will show up in game.

With that said, if you watched this event back on Nov 10th and never received these items, please let me know and I will be more than happy to look into this for you!

When purchasing Bundles and Ancient Coin packs for Sea of Thieves, it is important that you purchase through the correct store for the platform in which you are playing. Otherwise you may not receive the items in which you have purchased!

So this means that if you are playing on the Steam version of Sea of Thieves, then you must purchase your content through the Steam store. And likewise, if you are using the Microsoft Store or Xbox version of Sea of thieves, then you must purchase your content through the Microsoft Store.

This is due to how your purchases are redeemed into your game. For example, purchases through the Steam Store are added to your Steam Inventory, which in-turn are 'consumed' into your game during the next boot flow with the item then being removed from your Steam Inventory (the Microsoft Store / Xbox versions are not able to process these purchases). Likewise with the Microsoft Store / Xbox Versions, purchases through the Microsoft Store are not added to your Steam Inventory and therefore cannot be 'Consumed' into the Steam version of the game.

If you do mistakenly purchase Bundles or Ancient Coin packs on the incorrect platform store, please contact the following support channels for a refund.

• Support.Microsoft.com
  
• https://help.steampowered.com/
  

Thank you for watching the Sea of ​​Thieves broadcast: Mixer Invitational - Battle for LA. Your Onyx Four Pack MixPot package is ready and waiting for you in the game - we apologize for the confusion.
When you launch the Sea of ​​Thieves game, you'll find the following four items in the equipment chest: Onyx Bucket, Onyx Compass, Obsidian Drum and Black Dog Concertina.

Yes, I successfully redeemed the code in the xbox app, but the skins are still not credited to my account in the sea of ​​thieves.

Obsidian Eye of Reach Pack