Reproduce with one room type, a short future date range and a known guest count. Confirm the Rooms and Search Availability permalinks resolve to the intended language, the check-in date is before check-out, the site timezone is known and the room capacity can serve the requested adults and children. The server derives required room quantity and rechecks availability inside the booking transaction; a browser display is not an inventory authority.
If a room is missing, inspect publication state, room inventory, capacity, seasonal price and feature flags before changing templates. If availability is stale, bypass page and object caches for the test and verify the response after the cache is cold. Do not “fix” an unavailable result by deleting a booking or an external block. iCal external_block rows occupy the shared inventory path, are read-only and remain enforced even when Pro or its license is unavailable.
Check the room lock and final availability recheck when two requests race. A single failed search with a healthy server can be a configuration or date boundary issue; repeated deterministic failures across a clean test point to a product defect. Record the request locale, room ID, dates, guest counts and redacted response class.
Before escalation, verify Room Detail, Book Now and a no-JavaScript request so the symptom is not only a theme enhancement. Never expose guest data or signed booking parameters in screenshots or logs.