Okay, where's the download status/button gone to?
This is rather strange.
I can reproduce this by using Cmd-A (on Mac) to select a large group of books.
But If I scroll down through the library and select them manually (using Shift-Click) I can select a much larger group of books and still have the Download / status button show.
With my entire library in the Library panel, I typed Cmd-A, and received the Download Status for each resource.
^^Works for me as well, with my entire library or a subset. (Windows)
I can't reproduce the issue on Mac (v41 beta).
The problem disappeared when the application was shut down overnight despite being reproducible last night. I would suspect some unintentional persistent data.