Missing Warthog DLC key

I'm having the same problem as Luther. Redeemed the DLC, but no warthog. Could you have a look at mine as well, Misses Q?

According to this FAQ (scroll down for Warthog section): https://forums.forzamotorsport.net/turn10_postst64402_Forza-Horizon-3---DLC-and-Editions-List.aspx?=

The only way currently is to get it from the auction house or wait for another 'Forzathon' where this is the prize car.

The Warthog is a special access car in FH3 that is similar to Barn Finds in that anyone can drive one and buy/sell it in the Auction House, but it isn't available in the Autoshow to buy. The August announcement of the Warthog included a DLC code for Halo
players (sent via Xbox Live Message), which was distributed throughout the month of September. (If you redeemed your code, go to My Games & Apps > Manage Game > Warthog Details and click Install.) Unlike other promotional DLC or regular DLC cars, this DLC
was a gift car which added the car to the player's garage but not the Autoshow. Players who missed the opportunity to get a gift code from playing Halo will be able to win a Warthog from an October Forzathon event requiring multiplayer playground games wins
(seen in Achievements). Players who miss either opportunity may buy a Warthog from the Auction House without the need for DLC.

Miss Ghidorah,

The Forza Horizon 3 Known Issues thread doesn't specifically address the issue of the Warthog DLC not appearing in-game after redeeming the code.

I have all the DLC from the new game code, but the Golden Key is missing...

Same Issue, after deleting demo and warthog dlc, the Warthog is gone forever. I've checked also giftbox and garage. Nothing