I can no longer sync ebooks saved on my laptop to my iPhone
I've got a MacBook air running Monterey 12.6 and an iPhone SE running IOS 16.1.1.
I used to be able to transfer ebooks (some of which were purchased through apple, some of which were not) that I had on my laptop to my phone though the sync menu, similarly to how I can copy music from one to the other.
However, I am now unable to get any books to sync. They don't even appear in the window to give me the option to copy them over. Opening the books application still shows everything, as does finding the files themselves, so they weren't deleted by mistake.
Other media still transfers normally. I do have one book (which was purchased by a member of my family sharing group, not by myself) that still appears, but it's not the most recent purchase, the most recently read item, or anything else that I can determine that would make it different.
Any suggestions?
MacBook Pro 13″, macOS 11.2