reproduced in IE9, Firefox 19.02, Chrome 26.0.1410.64 m in 64-bit Windows 7 Enterprise
Child elements are not being animated when using the animatedClass feature. e.g.
I believe this is down to this line of code in jquery-ui-1.10.1,
allAnimations = o.children ? animated.find( "*" ).addBack() : animated;
o.children is always undefined as it is the return value from the $.speed call, I believe this should probably be,
allAnimations = animated.children().length > 0 ? animated.find("*").addBack() : animated;
however, the animation can be slow for elements with a large number of children.
The best fix would be to probably identify which elements would be affected by adding the class to the root element and only animating those elements.
A quick fix is to add a childSelector argument to only animate those children defined by the calling client code, this is a bit of a smell but is probably the best solution for performance.