The Recently Played albums in the Overview section of the web app seems to reset at random intervals. What causes that playlist to reset, or remove some of the albums?
It doesn't really reset, but it might have to do with how the recent albums are determined.
Whenever a file is requested, it stores the storage together with the path and time it was requested. Based on that it looks which albums correspond to that in the database, which are then the recently played albums. This means:
Especially the latter might be why it seems like the recently played list doesn't update, because Astiga simply does not know that you played that file.
I don't think that explains the behavior I'm seeing. I use the web interface the most frequently, so all my descriptions that follow will be based on that. What I'm seeing is I'll have, for instance, 10 albums in my recently played list, that correspond to my 10 most recently played albums. I'll browse the library and play some music, but then, for no obvious reason that I can see, when I browse back to the Overview page the Recently played list will be down to just my most recent 2 or 3 albums. The rest of the list will be gone. So it's not so much that it doesn't update, it's that it truncates itself seemingly at random.
Ah, yes, that might be because it only looks at the last 200 songs you played. It looks at the last 200 files you played, looks up the album for every file, and then gets the unique top 10. If you have only played three different albums in the last 200 songs, then it will only list those three albums. The reason is that otherwise the page would be even slower than it already is.