Hello there @B00MSIE!
I'm sorry to hear that you've had some trouble locating the small windmill. Thanks for sharing a video! It looks like the small windmill is there in your inventory. You can see it in the left-hand column at 0:55. Can you check again and see if you can place it in your settlement successfully?
You'll be receiving the error as you already have a small windmill in your inventory. The error is there to stop you from buying the item with your opals multiple times.
@Shanmae7 - I'm sorry to hear that you've been unable to locate your small windmill as well. Would you be able to send us a video which shows the following:
- You've purchased the small windmill decorative item. You can check this in the Animus Store by looking at what you've purchased.
- That you're missing the small windmill when trying to place a settlement decoration. Please show all of the available items you can place in your settlement clearly, so we can see the small windmill is missing.
I'd recommend uploading your video to a sharing platform, such as YouTube or Google Drive, as this will allow you to post a shareable link within this thread.
Thanks!