I have noticed a strange quirk with Sonarr and it pertains to the History in SABnzb.
I sometimes download whole series and many at a time. Sonarr seems to keep track just fine during the active download process showing hundreds of downloads but once the download moves into processing in history, Sonarr loses track of it entirely (limit to 30).
There is a workaround but it depends on the user and sadly this doesn’t fit my use case.
One could enable remove from client on complete. It will eventually purge history as it Imports files and then the older history items will become active. this would be great if I was only using Sabnzb. However I have a private tracker that I host files for using rtorrent and new downloads that happen to pull from that index should not be deleted at all.
I came across this Issue on github and I strongly encourage more development on this.
Ideally the solution is figure out why the API is only monitoring 30 downloads in History since History is actually downloaded and post-processing.