You’re talking about this checklist, correct?
Auto-population of place checklists is a little buggy and is being phased out soon. Depending on what you want to do with the data, there are a few alternatives. You can just browse the species list for your place: https://www.inaturalist.org/observations?place_id=163240&quality_grade=research&view=species
However, that view is limited to 500 species, so you could export the observations from that place and filter to unique species, or you could use this external tool built by pisum: https://jumear.github.io/stirfry/iNatAPIv1_observations_species_counts.html?place_id=163240&quality_grade=research
Previous bug report: https://forum.inaturalist.org/t/place-checklist-doesnt-show-all-research-grade-species-observed-in-that-place/11609