Question for folks please ... on the GC Home page filter options (as well as mobile) as well as other API partners (Cachly for example), I do not see a way to filter by negative attributes. For example, one might want to build a fizzle challenge based on "Not Available At All Times". To be honest, I am not sure a checker could be built within Project GC.
However, if I look at My Geocaching Profile, I have the ability to see progress on Negative Attribute Fizzys.
I am not a well-versed API expert, but I am wondering how that is possible? And then not possible through other filtering efforts.