A collection search can return every result matching your query while still showing only a small part of the institution’s holdings. “All results” belongs to the search conditions, not necessarily to the entire collection.
Record the query, filters and collection portal you used. A material filter, image-only option or department selection can remove relevant records without changing the words in the search box.
Test one known object if you have its identifier. If it does not appear, check whether the search covers that department or record type before concluding that the catalogue is incomplete or the object absent.
For a research note, distinguish no matching result, no digitised record located and no object known. These statements require different levels of evidence; a single unsuccessful search supports only the narrowest appropriate observation.
Try a documented alternative term or identifier rather than endlessly repeating the same query. Keep the route that worked so another reader can reproduce it.
An online catalogue is valuable precisely because it makes records accessible, but its interface also shapes discovery. Writing down those conditions turns a search result into usable research evidence rather than an apparently exhaustive inventory whose boundaries have disappeared.
Image: an editorial illustration, not a documentary photograph.