@Grégoire13, it isn't magic, it is not unexplainable, and it definitely is not random.
However, it is complicated and a bit unpredictable (which is not the same thing as unexplainable).
When a guest searches on AirBnB for a place to stay, AirBnB will show them at most 300 listings. There might be 2,000 or more listings on the map where they are looking, but only 300 will be displayed.
Which 300? In theory, the 300 listings that best match what the guest is looking for. Exactly where your listing ranks on the search results will vary depending on what the guest is searching for, but the important thing is this:
If your listing is not in the top 300, it will not appear.
If you city only has 300 listings, then great! Your listing will always appear.
Your listing is in Paris, France.
Paris has more than 40,000 AirBnB listings. This is the most listings of any city in the entire world.
If a person searched all of Paris, only one in every 133 listings would appear.
Certainly your area of Paris has more than 300 listings. Sometimes your listing will be in the top 300. Sometimes it will not. When your listing is not in the top 300, it will not show on the map.
Get your listing to rank higher in the search results, and your listing will appear more often in the top 300.
Rank lower, and your listing will appear less often.
This should not be a surprise.
It is aggravating. It is disappointing. It is frustrating.
But it should not be a surprise, or a mystery.