Reading amnesia

Not too long ago, I borrowed a book from the library because the description sounded interesting. I started reading it, and about thirty pages in, I ran across a scene that seemed familiar. I couldn't remember if it just resembled a scene in another book I'd read or if I had in fact already read this book. Fortunately, I've been recording all of the books I've read the last few years on Goodreads, and when I looked it up, it turned out that I had read the book already!

This isn't the first time this has happened to me (and fortunately it's a rare occurrence). I thought I was just getting old and forgetful. Then I ran across an article about reading amnesia on Bookriot, and I realized I wasn't the only one. I also felt better knowing that it had a name!

Why does book amnesia happen? I don't know about other readers, but I forget that I've read a book when:

• The book isn't memorable. That's the most obvious reason. If there was something memorable about the book, such as the plot or the protagonist or writing style, I wouldn't forget it. The Goodreads rating I gave the book from the library was 3 stars, which meant it was just meh and nothing stood out.
• The blurb is misleading. Sometimes a book's blurb will promise something that doesn't pan out. The blurb will hint at a plot line that isn't the main focus of the book or suggest a genre that doesn't match the actual contents of the book. Regarding the book I had borrowed, its blurb led me to believe it was a taut thriller, but the first thirty pages were anything but thrilling. It was only when I ran across the first scene that caught my interest that I realized I may have read the book before.

Have you ever suffered from reading amnesia? If so, what causes it for you?