My header images don't rotate anymore after updating to newest theme version

After using the Atahualpa theme for awhile and really liking it, I had plans to create my own "seasonal" header images and was imagining how they would look as they did the rotate & fade thing which is so unique... But then after updating to the latest version, there is no longer any rotation, waah. I haven't created any new images yet, I won't till I get this problem sorted!

Can anyone advise, please? I'm sure this issue has been discussed elsewhere on the forum, but I haven't found any threads yet that would be a "tutorial" for me...