Does the data presented in that article really suggest that the apartments are actually empty or is it simply that it takes a while to sell out a new developmen

Does the data presented in that article really suggest that the apartments are actually empty or is it simply that it takes a while to sell out a new development? It's going to take a while to move a hundred units, especially if you want to increase the profits. The StreetEasy report the article is inspired by actually shows that in 2019 there were more condos sold than completed.