Right now questions tagged soapi.cs returns a HTTP status code 404 (for various HTTP clients) while questions tagged soapi.js does not.

Interestingly though, soapi.cs seems to work just fine in other places, e.g. Newest soapi.cs questions returns the desired result, and so does Stats on soapi.cs. That is, as soon as (sort) parameters are included the route seems to work as expected, but not without?

What's the magic difference here?