I didn’t see this specifically addressed and maybe this should be a feature request but I thought I’d check here first. I know @bouteloua addressed this in the previous thread, https://forum.inaturalist.org/t/search-query-for-observation-field-values/8056, indicating that by clicking on the Observation Field you can search, but I was wondering why the Observation Fields aren’t included in the filters all the time. It kinda necessitates finding an observation with that field result to search by it.
I was interested in the Observation Field result, “Yellow Ratsnake - Pantherophis alleghaniensis quadrivittata=formerly known as”. Once I found one I was able to search others and, in the filters, it now showed a searched Observation Field,
I know there is the iNaturalist API, but that is a little daunting (at least for me) and you have to go to to an additional site. If it were just in the filter, it would be ever so much easier.