Ok, I searched the forums, and thankfully, I found another thread in which a user suggested converting the EPUB to MOBI and then back again (e.g. using an online converter). It worked! I naturally hope (especially for new users’ sake) the underlying problem will be solved, but this hack took me 1.5 minutes to execute, while I’ll likely spend 30 hours reading my current book, so it matters little to me. 