Hey Joao!
From your description, it seems like you need to scan more of your space before creating the anchor, which will improve the results when you are querying the anchor.
You can find more details on this concept page. You can maximize the viewing perspectives by walking around the room and driving up the value of SessionStatus.RecommendedForCreateProgress, and should capture the unique and stable features of the spaces other than those on the chair, so that ASA can recognize the difference between the spaces.
The same concept applies to capturing more of the surroundings when finding anchors calling CloudSpatialAnchorSession.CreateWatcher.