I’ve seen this before with large numbers of observations. I think the number being returned by the search is higher than the actual result set for some reason, which means that the higher page numbers have no results in them.
Either that or the paging is out, so instead of 260 pages of 20 results, there is only 104 pages of 50 results (as an example), but it’s showing there is 260 pages
I have also encountered this, it seems that every so often, I can get results to appear on a high page. But I can’t seem to find a reliable scenario in which it works.
This is due to a 10,000 record limit iNat sets on searches so that they’re not too taxing on our system. I recommend adding more filters to your searches to reduce the total number of observations returned (eg try restricting to a genus of Pierids, and/or restricting the search to a place) and splitting up your search that way.
Oh rats! Is there a way to generate a species list for an area? For example a list of Pieridae for North America and then I can search the main genera perhaps.