However, I found, to my surprise, that Numista finds no coins for the issuer... yet shows me as having 4 coins from it.

(I've expanded the options to confirm that I didn't accidentally exclude anything.)
The issuer is listed in some contexts (e.g. my own coins list) under Livonia - Swedish, and in other contexts (e.g. search results) without any specific upper categories.
The country list agrees with the search results in that the only 3rd level issuer under the Livonia - Swedish 2nd level category is Livonia - Swedish; no City of Riga to be seen anywhere.
Any ideas what the triangular heck is happening?
(I suspect it's a slight reorganization that hadn't hit some areas of the website yet, but it still looks pretty darn weird.)