It turns out that I have so many books stuffed away in my Amazon cart’s “Saved Items” section that I’ve exceeded the maximum limit.
In case you’re wondering, Amazon won’t let you store more than 600 titles in that list.
All very annoying, as I use that feature as a kind of unofficial “read one day” list. When I hear about a good book, I go off to Amazon and add it to the cart. Now I will need to rethink my strategy.