Issues Downloading onto iPad with Content Server and Calibre Companion

[jesscat]

I have CC on iPad. I have no issues connecting to Calibre on my desktop wirelessly or via the content server. Calibre is updated to within a version or two of current, and CC is current.

I have two Calibre libraries, one of which I use regularly, and I can use the content server to access or download books in that library from my iPad. I haven’t accessed the other library for quite a while, but yesterday I got an urge to read something from that library and switched to it on CC while connected to the content server. The books in the library were all shown and listed as they should be, but I couldn't access any of them. When I tapped on a book entry nothing happened, and when I selected “download,” the spinning wheel spun indefinitely, until I gave up after many minutes (downloads from the other library are almost instantaneous).

I double checked that the library works correctly when accessed directly from Calibre on the desktop - the books take a little while to open since they haven’t been opened in a while, but they all do open, the books are where they are supposed to be, etc.

Any ideas what might be causing this?

Thanks!