Economic vacancy is not an insured peril
Loss of rent responds when an insured loss makes a property unrentable. It does nothing when demand falls, an employer reduces staff or a season is quiet. That is a business risk of owning a rental in a concentrated market and it is uninsurable, which is worth being clear about rather than hoping.
Long vacancies engage the policy anyway
Even though the cause is economic, the consequence is a building standing empty, and most policies restrict cover after a stated number of consecutive vacant days. A market-driven void can quietly cross that line while the owner is focused on finding a tenant.
Seasonal demand suits some products better than others
Where the market genuinely runs in seasons, a property may do better as a short-term rental for part of the year, which is a different product and a different policy. It is worth deciding deliberately rather than drifting between the two.