I purchased Diablo 4 on 12/12/25. It shows a completed purchase. I don’t have the chess set item.
I purchased in February and I have the same problem.
I filed a ticket and a GM told me that changing your Battle.net password causes all of your games to resync with the servers, and that might get WoW to recognize the purchase. (News to me; it was worth a try but it didn’t work for me.)
So the next step is to file a bug report which, according to their own help pages, I’ll never get a reply. I just have to hope that it gets fixed, I guess.
I know the decor is part of a bundle but the fact remains that I paid good money for something and I haven’t gotten it. This does not motivate me to spend even more money in the store.
Looking at your collection you appear to have the rug and the chest. I believe it’s called Hatred’s Wolfpelt Rug and Prime Evil’s Chest.
I am not seeing the chess set though, so please submit a ticket under Purchase Failure and let them know.