Debug Info

https://github.com/zkoss/zk/blob/4efeeef5c4671a42e563e05a31d1797a75b10e01/zk/src/archive/web/js/zk/anima.js#L199-L203

animate() calls that use a complete:callback as part of the option list will trigger the callback if the animation completes successfully.
If the animation ends without completing for any reason (browser handling, property error, interupted, etc), the complete:callback will not be invoked, which prevents the animated component from triggering afterAnima (or any other relevant post-animation logic).

Root Cause

Solution

JQ animate supports the always:callback in addition to complete:callback
always will always be trigger when the animation finishes, regardless of state. (It acts as a "finally" block)
As such, it should be prefered for callbacks that needs to be invoked at the end of the animation.