Lesson list pagination incorrect

On the Manage Lessons page, no matter how many lessons I set it to display per page (20, 50, or 100), the number of lessons that actually gets displayed per page is essentially random and never matches what I set it to. Note that this only occurs when I've selected something other than "All Active Lessons" in the "Show" dropdown box. For example, if I choose "Intermediate Group" from the dropdown and set it to display 20 lessons per page, it might display 14 lessons on the first page, 12 on the next, and so on...