I have a paid sub to NZBGeek.
I’ve been missing a lot of shows (but not all shows). Manual searches come up with nothing.
And these are mainstream shows.
I used some other online NZB search engines and input the specific shows and episodes I’m missing and they return no results, so it doesn’t seem to be an issue with NZBGeek.
Should we be concerned that maybe the days of Usenet are waning? That would be sad.
Did you check the list of groups you want Sonarr to search with your indexer?
Do you meet the max number of API hits with your indexer account? Level up to a premium account.
My personal experience is that you don’t need more than one indexer if you use a ‘good’ one.
Dunno which indexer you use but I can send you an invite from mine (which works fine for several years).
I do not think it is fizzling out, but it has never been a reliable medium for all shows for a variety of reasons. As said elsewhere, you probably need more than one indexer, and probably also need a torrent indexer or two too (with download client as well obviously) to occasionally fill in the gaps.
For newly broadcast North American shows, there is almost never an issue with Usenet, but for older ones (or even current series but back a few episodes), things do disappear because of DCMA takedowns.
For British shows though, Usenet is not a reliable medium, but then neither are Torrents as there is just not the community of uploaders there are in North America, and those there are, seem to prefer other platforms to share (like Google Drive) that are not easily indexable and auto downloaded… but that is a while different thing.