I was told by the host that I could leave the luggage at reception before the morning before check-in, however, in reception they told me they do not do consignment, and that is the host ho was this custom, so I could leave my things rear the elevator (at a place where it was not visible, but also not protected by anyone).
The other aspects of the stay were pretty good, the apartment is like the photos, the host was responsive with an air conditioning issue we had, and everything was clean.
The zone is rear a parking near Chamartín subway station, at first not so easy to find but when you know it, it is easy no access. Well connected by subway Line 1 and various bus lines.