Why a particular space is missing
Only published spaces appear in the results. Every listing is reviewed before it goes up, and a listing that was paused or removed leaves the results.
A removed listing is not deleted. It goes to the archive, and if its owner brings it back it returns as a draft and is reviewed again before it is published.
If you added dates, a space can be missing because it is taken, because the host's notice period has not passed yet, because you asked for a date too far ahead, or because it is not set up to take bookings at all.
If you added a budget, it is measured against one price unit. Choosing a unit drops from the results spaces whose hosts did not price them in that unit.