Akismet spam handling since version 2.1.8

Since upgrading to version 2.1.8 on two sites, Akismet is not moving any spam comments it finds to its Spam queue. Instead, they all appear under Manage Comments. If I hit “Check for spam,” they are correctly moved and appear on the Akismet “Caught spam” page. Has spam-handling been changed in this version? It’s definitely behaving differently in the past week or so; I’ve been running Akismet for over a year and it’s never done this before.